So, about a month ago I was doing towel drills and popped something in the muscle of my throwing shoulder, on the back side of my shoulder. It was in the center of the meaty muscle right underneath the bone of my shoulder. It didn't quite snap, but it felt close to that, and it immediately hurt pretty bad. Every time I would extend my elbow (do a forearm chop from a stand still) it would kind of burn with pain and I could feel it twinge.
So I laid off for about 5 days and felt back to normal. But since then I've had the thing start to burn again twice, both times the morning after back to back days of playing. I'm guessing it's just a muscle strain that never fully healed(?) Besides resting it, what should I do to help it heal? It bothers me that it keeps popping up after heavy use. It feels like a deep bruise or something.

