I have had this injury one each over the last three years in varying degree's. My PT says it is due to a strength issue. He has me doing what I call declines with the injured muscle. Without using the injured calve, use the other leg to raise yourself as high as you can off the floor on your toes (healthy leg). Then place other foot on the ground(on toes) and add as much weight to the leg as you can without pain and lower your body down with both legs. 3X by 12 each day. Slowly start adding more weight to the injured leg as you decline. Eventually going to putting all your weight on the injured leg as you decline. Then do on a stair where you can decline below the normal floor level.
Good advice earlier in the thread about coming back slowly!!!!!!