Flexi Says: The menstrual cycle is a monthly cycle of changes in the ovaries and uterus. During menstruation, blood and other tissues from the lining of the uterus are shed and exit the body. Many teen girls have painful menstrual periods. They typically have cramping in the lower abdomen. Generally, this is nothing to worry about. Taking a warm bath or using a heating pad often helps. Exercise can help as well. A pain reliever like ibuprofen may also work.