For instance, a teenage girl may experience pain during menstruation (a symptom called dysmenorrhea). Some parents pass it off as normal, since they’ve experienced it, too, while others are distressed and anxious for the child since the symptom could be a sign of endometriosis. Endometriosis is characterized by tissue, similar to uterine fragments, implanted in the ovaries, fallopian tubes, and even the areas close to the bladder or rectum. The abnormal location produces painful sensations during menstruation, as well as excessive bleeding, painful urination, and diarrhea or constipation.
http://www.indiancrestpeds.com/info-article/westminster-pediatrics-teen-girls-period-problems/