Hi and welcome, The symptoms may be caused by many conditions. The most likely is endometriosis where the endometrium [uterine lining] may implant in the abdomen and causes bleeding inside during periods. Other causes may be pregnancy and threatened abortion if having unprotected sex, fibroids, infection, ovarian tumors and endometrial polyps. You will need an examination by a gynecologist, ultrasound and a urine pregnancy test for diagnosis. Treatment will depend upon the cause. Hope this satisfies your query. Thanks for using HCM. Feel free to ask any more questions that you may have. Dr Madhuri Bagde Consultant Obstetrician and Gynecologist