Pain in the left buttock, especially when turning over, is most commonly caused by a herniated lumbar disc, which occurs mainly as a result of chronic strain. Patients are mostly middle-aged and elderly, and prolonged strain or bone degeneration can lead to nucleus pulposus degeneration. Predisposing factors include protrusion of the nucleus pulposus after strenuous activity, which can protrude into the peri-vertebral canal or cause compression of the nerve roots and compression of the sciatic nerve, resulting in hip pain and, in severe cases, limited movement of the lower extremities. In this case, the patient should first be treated in bed, in a hard bed, and should be advised to take oral pain medication and apply nerve-nourishing drugs, or choose physical therapy.