I have been having pain between spine and left shoulder blade area which I thought must have been something to do with disk herniation. But on closer look and some thinking, I feel that it is a rib muscle that I might have sprained or pulled. This pain started back in 2011 and I took break from tennis for a long time and played a session again last week. Pain returned immediately. I have pain when I rotate my core for forehands from right to left. How come a muscle sprain or pull is so persistent for two years? What can I do to recover from this? Can you suggest any exercises? How can I prevent it in future? Do I need to strengthen any specific areas? Thanks a ton!