What would cause a sharp tearing pain in calves when running or g?

Cramp : It could be something simple like muscle cramp or more serious peripheral arterial disease. The blood supply is compromised in the latter and warrants to see a vascular surgeon. First see your pcp for initial evaluation

Gastroc.: See physician if this is a chronic problem. Sharp pains in the calf when running is most commonly the medial head of the gastrocnemius muscle. Partial tears in middle- aged adults to this muscle are extremely common. If there is any concern about blood clots see your pcp immediately. Good luck!