Mastitis, which mostly affects women who are breast-feeding, produces redness, swelling, and discomfort in one or both breasts. These are all signs that something is wrong and you should call your doctor. You should call your doctor if you have any concerns about your health during pregnancy or breast-feeding. Your doctor will conduct a complete medical history and physical examination to ensure that you don't have a more serious problem that needs attention. He or she will also ask you questions about your symptoms and perform tests to determine the cause of your pain or other problems. Doctors usually can tell whether you have mastitis by feeling your breasts. They'll notice increased firmness and tenderness of the breast(s) where you have mastitis. If this is the case, your doctor may suggest that you not pump your breasts. This is because pumping forces bacteria up into the milk ducts, causing further infection. Your doctor may also recommend some type of antibiotic treatment for mastitis. Mastitis can sometimes lead to bacterial infections of the breast ducts (endometritis). With this condition, the breast tissue becomes red and swollen, just as with a case of acute mastitis. However, with endometritis there is also often pain with menstruation cycles or during sexual activity.