Painful menstruation is called dysmenorrhea, and refers the pain that occurs around the menstrual, or bleeding, phase of the cycle. There may be other associated symptoms like nausea, fatigue or diarrhea. While many people experience some cramping with their period, some have pain severe enough that it keeps them from doing their regular activities. They may rely on pain relievers and heating pads, but sometimes that is not enough. There are many possible causes for dysmenorrhea that can be explored with a gynecologist - endometriosis, adenomyosis, fibroids, cysts, hormone imbalance, heavy periods, low back injury, past or present infection, pelvic nerve compression, pelvic inflammatory disease.