My left should has always been 'crangly'. When I say 'always' I mean for at least 30 years. A sport masseuse friend several years ago voiced the opinion that I must have had a broken shoulder blade at some point - the shoulder blade rubs on my ribs. There is now lots of knobbly tissue on my ribs under my shoulder blade.
Like lots of these things, I've never bothered with going to the docs about it; they don't really treat low-level chronic conditions anyway. It doesn't stop me working and it isn't endangering my life.
It does sour things, tho'. Now it hurts most of the time. In some ranges of movement it gets 'stuck', and needs a bit of encouragement to free it up.
I know some movement and stretching exercises, but these don't actually seem to help.
I've just googled on my symptoms and too my surprise found a perfect description:
http://www.eorthopod.com/content/snapping-scapula-syndrome
