I've been having some minor trouble with my shoulders on and off for the last few years. I think some of it came from skater hockey (yes, like ice hockey), and the result is that sometimes my right shoulder is too sore to lie on for any length of time in bed. The left one is not as bad, but there is still a niggle. I can use my arms normally, btw, and there don't appear to be any mobility or range of movement problems on either side. Given all my skating and cycling, my shoulders and arms are pretty skinny and lacking in muscle, and ridiculously so when compared with the lower half.
I know I should really see a physiotherapist, but perhaps someone here has a good link on some exercises I can do to sort this out?