The main reason is that the pelvic congestion during menstruation leads to lumbosacral pain. If you have pelvic inflammatory disease or get cold or angry during menstruation, or if you are overworked, it may cause the menstrual blood to be discharged poorly, and you may have lumbago, lumbago, and buttock pain. If the pain is more severe, you need to go to the hospital for ultrasound to see if there is endometriosis or adenomyosis, the pain is progressively worse and needs to be treated in time or it may affect pregnancy. If the result is not good, you may need to do surgery.