Just getting over one myself. I didn't see a doctor, but I'd put it somewhere between a Grade 1 and 2. It took about 4 weeks before I was playing again, but it still gets tight when I play sometimes.
One of the people I play with is a PT and she told me adding some cushion to the heel takes some strain off the calf. It seemed to help me when I was recovering, but I ended up removing it after a few weeks. Now I'm getting tightness again, so I may put it back.
I also wear one of those Zensah calf sleeves. That seems to help a lot.
I'm also focusing more on tennis specific workouts and gradually adding exercises to build up the muscles for the quick, explosive movements tennis requires.