Sudden pain in the foot like a cramp may be due to calcium deficiency, lumbar disc herniation, foot muscle trauma. 1. Calcium deficiency: calcium ions have a stabilizing effect on nerve cell membranes, preventing abnormal membrane potential discharges and reducing neuromuscular excitation. Calcium deficiency can cause neuromuscular excitation, triggering spasms and convulsions, leading to foot pain like cramps. 2. Herniated lumbar intervertebral disc: the herniated intervertebral disc tissue stimulates and compresses the nerve root, resulting in lumbar pain and pain in the outer thigh, outer calf, up to the root, the dorsum of the foot, which can be manifested as a sudden pain in the foot like a cramp. 3. Foot muscle trauma: impact, extrusion, sprains caused by foot muscle injuries, resulting in muscle spasms, so that the foot suddenly like a cramp like pain. The foot suddenly like a cramp like pain may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.