Hi. Thanks for your query. Noted the history and understood your concerns. Gastrocnemius is the muscle of the calf, situated on the posterior aspect of calf area is very strong as it pull up the whole body weight while walking and running. Since you have pain in this muscle on left side on upper or superior aspect the causes can be as follows: Strain in the muscle while doing some activity. Thrombosed veins in it, can also cause local swelling and if the deep veins are involved swelling of the whole lower part. Herniation of muscle. This can be ascertained by the following ways: Consult an Orthopedic Surgeon for clinical evaluation, examination and thus get an appropriate clinical diagnosis. To be further clarified by Ultrasound and color doppler examination to get an exact diagnosis so that a proper management can be done. Till then take a full rest. If there is local muscle problem an anti-inflammatory medications with support can help relieve pain. If the is deep vein thrombosis you will need a long medical management. If there is herniation, closure would be required.