A while back in September I was benching with DB's, when I set the weights down I was still laying down and managed to tweak my left shoulder. I took about a month and a half off from lifting and have been ever since. Unfortunately, I can't really work out my shoulders and when I bench my left arm slows me down because the shoulder on that side is so much weaker than the other. Not only that but I just started muay thai about 2 months ago and this little injury has managed to suck most of the power out of my jabs. After 25 minutes or so of practicing it tires out, becoming useless almost. Its been pretty frustrating and I'm sick of this holding me back...I don't know whether its my rotator cuff or something else in my shoulder, but how should I go about strengthening this so it doesn't hold me back in practice or at the gym?