Your period or pregnancy aren't the only reasons your boobs hurt. Learn what experts say are just a few of the otherwise everyday things that can cause your boobs to hurt — sometimes really badly.

Do you blame most of your boob pain on your period? It's true, that can be why your boobs hurt or just feel extra tender. "Many changes are due to fluctuating hormone levels," says Richard Bleicher, M.D., surgical oncologist and director of the Breast Fellowship Program at Fox Chase Cancer Center in Philadelphia.

But different stages of your menstrual cycle can affect your breasts in different ways, and other factors — diet, medications, and certain activities — can influence your breasts too. In fact, while they may not be able to predict the weather à la Mean Girls' Karen Smith, your breasts tell you a whole lot about what's happening in your body and your health. Here, reasons why your boobs hurt so dang bad.

Potential Reasons Why Your Boobs Are Hurting

1. Exercise

In general, you're unlikely to notice any changes in your breasts even with an intense strength training regimen. That's because your breasts sit on top of the pec muscle, but aren't part of them. So you can develop stronger muscles underneath your breasts without affecting their size or shape, says Melissa Crosby, M.D., associate professor of plastic surgery at the University of Texas MD Anderson Cancer Center. However, a study from researchers in England who examined breast movement during exercise found that breasts bounce as much as 8 inches up and down during physical activity. All that movement could be why your boobs hurt so bad post-sweat, but the researchers also found that wearing a sports bra reduces bounce by up to 78 percent during aerobic exercise. Want to learn more about how your boobs specifically are impacted by exercise? Visit Shock Absorber, enter your cup size and level of activity, and watch what happens to breasts when you're on the move. (See: These Are the Absolute Best Sports Bras for Large Breasts, According to Customer Reviews)

2. The Luteal Phase

Your menstrual cycle is divided into two halves: your follicular phase, during the first part of your cycle (your period is day one), and your luteal phase, after ovulation. As estrogen and progesterone levels rise following ovulation, you experience an increase in blood flow to your breasts, which can increase their fullness, nodularity, and tenderness — a potential culprit for why your boobs hurt before your period. In a study of more than 200 premenopausal women who received mammograms in both the follicular and luteal phase, researchers found that breast density and size were greater in the luteal phase. "If you feel something unusual in your breast, track it during different times in your menstrual cycle because it may be due to changes in your hormones," says Dr. Litton. If your boobs still hurt regardless of what phase you're in, have your doctor check it out.

3. Changes In Weight

Your breasts are made up of breast tissue (including lobules and ducts that are called into action while breastfeeding) and fat tissue. So when you gain weight, your breasts often increase in size. When you lose weight, you may notice they shrink. This fluctuation could cause your boobs to hurt. The amount of fat each woman gains or loses in her breasts depends on breast composition, which isn't the same for everyone. Some women have denser breasts, which means they have more breast tissue and less fatty tissue. (Weight isn't the only thing that impacts breast type.) These women may not notice as large a shift in breast size when they gain and lose weight as a woman who has a greater proportion of fatty tissue would. (On the other hand, your breast size may have an effect on your fitness routine.)

4. Bug Bites

"I don't know why, but spiders seem to love breasts," says Mary Jane Minkin, M.D., professor of obstetrics and gynecology at Yale School of Medicine. "It can be really scary because you may develop a red, inflamed bump and women often think they have inflammatory breast cancer when it's just a reaction to a spider bite that can be cleared up with antibiotics." It's unlikely that inflammatory breast cancer (a rare, but very aggressive form of the disease) develops overnight, so if you suddenly notice redness, inflammation, itchiness, and swelling, it could be a bug bite. But still be sure to have your doctor look at it, adds Dr. Minkin.

5. Alcohol

Women often underestimate the impact booze can have on their breast health and therefore sometimes breast pain, says Dr. Minkin. A U.K. study of more than 28,000 women found that even low levels of alcohol consumption (less than one drink per day) increased the risk of breast cancer by about 12 percent. Scary stuff! It's not exactly known how booze boosts your risk, but it could affect levels of hormones, such as estrogen, associated with tumor growth. Drinking may also lead to weight gain and your risk of breast cancer rises with your weight. Bottom line, even if you're boobs aren't hurting, for your overall health, "stick to no more than one drink per day," says Dr. Minkin. (Related: What Young Women Need to Know About Alcoholism)

6. Pregnancy

Question: When do your boobs start hurting in pregnancy? Answer: Sometimes as soon as a few weeks after conception, but it's a common early symptom. The majority of changes that occur in your breasts during pregnancy prepare your body for breastfeeding. Blood vessels, ducts, and lobules in your breasts that are involved in producing and transporting milk expand and proliferate. This process can lead to tenderness, heaviness, and a significant increase in your cup size. You'll also notice your areola and nipples expand. (Related: All the Unexpected Ways Pregnancy Changes Your Body)

7. Sex

During foreplay, your heart rate and blood pressure increase, which causes your breasts to swell and your veins to become more prominent. This shouldn't cause your boobs to hurt though, so if sexual arousal or sex is causing you pain, let your doctor know. Your nipples become erect and the areolae — the area around the nipple — expand. A Rutgers University study even identified a link between areas of the brain that respond to nipple stimulation and those connected with clitoral stimulation. This connection may explain why some women can orgasm from nipple stimulation alone. (Here are more clitoris facts that will revolutionize your orgasm.)

8. Age

As you age, you may also notice that your breasts become softer and may start to sag, which could cause tenderness from gravity pulling on the skin. Breast density decreases with age so you have a greater proportion of fatty tissue than you did when you were younger. Plus, Cooper's ligaments — fibrous tissue that acts like an internal bra — stretch over time and may lead to drooping. Regularly sporting a supportive bra can help.

9. Birth Control Pills

Your doctor may have warned you already, but your birth control pills could be why your boobs hurt so much. "When birth control pills were first invented, they contained extremely high doses of estrogen and there were a lot of women walking around with very large breasts as a result," says Dr. Minkin. Today, most contain about one-fifth of the original amount, so they don't have as big an effect. Still, it's completely normal if you experience a little boost in breast size or your boobs hurt when you start birth control. "Estrogen can lead to more fluid retention and also increase breast tenderness," adds Dr. Minkin. If it's troublesome, talk to your doctor about other options.

10. Medications

Besides the Pill, certain other meds — especially some types of antipsychotic and antidepressant drugs — are notorious for affecting your breasts. One in particular, Risperdal, is a drug used to treat bipolar disorder. Risperdal can increase prolactin levels, which may cause your breasts to leak milk even if you're not breastfeeding, says Dr. Minkin.

If your boobs hurt before your period or really any time during your cycle, nonsteroidal anti-inflammatory drugs (such as ibuprofen and aspirin) can help. They may work by inhibiting prostaglandins that are involved in inflammation and tenderness, says Dr. Bleicher. Diuretics, often used to treat high blood pressure, can also decrease breast pain and swelling by reducing fluid retention, adds Dr. Minkin. While some minor boob pain and discomfort is considered normal at certain times during your cycle, talk to your doctor if your boobs are hurting so badly that it's impacting your lifestyle.

11. Caffeine

Sad, but true: Your morning cup (or three) can take a toll on your breast health. Some women's breast tissue is especially sensitive to caffeine, and fibrocystic breasts — a benign condition that can make your boobs feel lumpy or rope-like — can occur. For some, this can be incredibly painful and worsen around your period. Doctors don't know why this occurs, but if your boobs hurt you experience lumpy breast tissue, try cutting out caffeine for several weeks, says Dr. Minkin. If you experience severe soreness and nixing your coffee intake doesn't help, talk to your doctor.

12. Puberty

This is another estrogen-fueled change that can cause your boobs to hurt. Puberty occurs in stages: At first a breast bud — a small raised bump under your nipple — starts to grow. Next, the nipple and areola grow larger and darken in color and over time breasts continue to grow. They don't always sprout at the same pace — one may be larger than the other for a long time or even forever. This is why your left boob could be hurting while your right feels fine. It can take several years for your breasts to reach their full size. What else to look forward to when this process starts? Your first period. On average, it starts about two to two-and-a-half years after breast development begins.