I've been having an issue or two with my left shoulder. Getting my arm over my head is a red hot mess and hurts like hell so I just don't do it. But having mentioned it to my trusted chiropractor (who is the best on the planet) she seemed to think that it would be better to investigate what was going on and devise a way to remedy it. So first she engaged in neurological and functional testing (or eliminating the possibility of someone actually having gotten on my last nerve and fucking it up). So neurologically I'm intact (yay!) but my left shoulder blade doesn't move when I move my arm which jacks the head of my humerus into the joint socket and tends to cram the soft tissue structures together and cause pain. Apparently, this requires that the musculature of my lower rotator cuff and lower trapezius has to get cracking and pull this puppy down on the rib cage and out the way. Currently, I'm on two exercises to facilitate this change and of course I've over done them and now my upper back/shoulder hurts. Which simply means that it's time to bust out the ice.
And I'm guessing this is due to my unfortunate preference to sleep on my left side. Damn it. I'm barely trainable when I'm awake and alert, forget when I'm asleep.