There are many possible causes for sudden pain in the hip, the common ones are as follows: 1. There may be trauma here. For example, if the patient falls while walking and lands on the ground, it may cause blunt contusion of the soft tissues here, and in serious cases, it may cause fracture, which may lead to pain. 2. It may be caused by cold. For example, if the patient sits on a cold stone surface, the cold may cause muscle spasm and pain. 3. It may be caused by overexertion. For example, if the patient walks long distances or does fitness exercises for the lower extremities, it can cause a large amount of lactic acid to be deposited inside the muscles, resulting in pain. 4. This condition may also be caused by peripheral nerve lesions. The pain may also be caused by adjacent joint lesions. For example, there may be osteoarthritis of the hip joint, femoral head necrosis, or dense osteitis of the sacroiliac joint, ankylosing spondylitis, etc.