As GCW says, these symptoms could be caused by a number of problems, many of which will be improved by less time locking off, and a little more time with some exercises that engage / strengthen your rotator cuff.
I suspect that like many climbers (actually all sportspeople) , when something hurts they sort of know vaugely what needs doing/ not doing, but they'd like a miracle button pushed to make it go away, instead of doing tedious, repetitive excercises when they'd rather be campussing / watching telly / in the pub. This certainly applies to me. Go do some yoga, its more interesting and fulfilling than therabands. ;-)