Sudden pain in the calf may be the cause of muscle injury, muscle cramp, phlebitis of the lower extremity. 1. Muscle injury: when the human body moves beyond its own capacity, such as over exertion of the calf may induce acute muscle strains, or even tearing, causing sudden pain in the calf. 2. Muscle cramps: Excessive exercise, electrolyte disorders, cold and other factors can cause local muscle contraction dysfunction, resulting in sudden pain in the calf cramps. 3. Phlebitis of the lower limbs: Phlebitis of the lower limbs refers to the inflammation of the venous blood vessels in the lower limbs mainly manifested as redness, swelling, heat and pain in the lower limbs, which can be caused by acute onset of the disease, thus leading to sudden pain in the calves. In addition, lower extremity deep vein thrombosis, occlusive vasculitis can also cause pain in the calf, such as the symptoms of sudden pain in the calf, you need to go to the regular hospital in a timely manner to clarify the cause, and the doctor according to the situation of the individualized treatment plan, so as not to delay the condition.