I recently noticed a pain below my shoulder (posterior) around the armpit of my right arm (I am right handed in Tennis). I poked around and found that if I press hard enough there is some pain on the right side but not on my left. It seems like a tendon is being stressed. I looked up shoulder anatomy pics and it seems to be the Teres Major, just below the rotator cuff. Funny thing is there is no pain doing any shoulder motions.. no pain at all during tennis or serving. I can lift weights, and have full range of motion , with no pain. I have started icing it. It seems better already, but will stop tennis till the pain completely goes away (probably less than 1 week) anyone have something similar?