If you have low back pain when you have your period, it is often caused by the following reasons: 1. If the uterus is in a retroflexed and retroverted position, the pelvic cavity is congested during menstruation, and the uterus will stimulate the sacral ligament when you have your period, so you will have low back pain. 2. If you have inflammation of the sacral ligament, the sacral ligament itself will be congested and edematous, and the pelvic congestion will aggravate the original sacral ligament congestion during menstruation, so you will have low back pain. 3. The original sacral ligament is congested, so there will also be lumbar pain. 3, because of pelvic inflammation, so menstruation will also appear lumbar pain. It is recommended that the necessary examination can be done after the menstruation is clean, and if there is inflammation, anti-inflammatory treatment is actively given. If there is no drug allergy, you can take oral broad-spectrum antibiotics, combined with the treatment of anaerobic bacteria metronidazole co-medication for treatment.