The symptoms of sudden hamstring pain are as follows: 1. It may be caused by fatigue fracture of the foot, which is related to long time repeated walking activities, resulting in repeated strain on the bones of the foot, causing fatigue fracture, resulting in obvious pain in the hamstring area. 2. It may be caused by degeneration and hyperplasia of the bones of middle-aged and elderly people, which can occur after long time walking. 3, may be due to acute strain on the fascia, ligaments and tendons of the foot, resulting in sudden pain in the hamstring area, affecting the normal weight-bearing activities of the foot, and causing significant bruising and swelling of the foot after serious injury. The injury can also lead to significant bruising and swelling of the foot.