The most common type of hamstring pain felt in the thighs is lumbar disc herniation, where a herniated lumbar disc compresses the nerve roots that emanate from the spinal canal and causes pain in the back of the thighs, and sometimes even in the calves. This kind of hamstring pain is mainly caused by nerves, and its treatment is mainly focused on treating lumbar disc herniation. There is also pyriformis syndrome, where the nerve, after coming out of the pyriform fossa, is compressed by the pyriformis muscle in this area, which causes pain in the back of the thigh and calf, just like tendon pain, which is also more common.