Many girls have swelling and extra tenderness in their breasts just before their monthly period starts or when they ovulate. This is not very comfortable, but it is normal. The soreness is caused by hormones, which make the breast tissue hold more water than normal. Wearing a well-fitting bra will help you feel more comfortable, and eating less salty food will help reduce the amount of water that your body is storing.
Periods can affect one's mood too.
Before their period starts each month, some girls feel tearful or depressed. Sometimes girls feel bad tempered because their breasts feel sore or their body feels a bit swollen or bloated. Try not to let it bother you too much. Many girls experience a bit of abdominal pain or cramps during their period. These cramps happen because the muscles of the uterus are contracting while the lining is being shed.