It is not normal for your period to remain unclean for half a month with back pain. At this time, first take bleeding medicine and anti-inflammatory drugs to control the symptoms. Because the back pain may be bleeding for a long time, caused by pelvic inflammatory disease. After the period is clean, you should go to the hospital for examination, which may be caused by organic lesions of the uterus. For example, endometrial polyps or uterine fibroids may present such symptoms. If there is no organic lesion in the ultrasound examination, we should suspect that it is caused by irregular menstruation. Most of them are caused by poor luteal function causing prolonged menstrual periods, in which case progesterone medication can be taken to adjust the menstrual cycle.