What happened to my left shoulder?

Woke up, and it hurt. Still hurts. Also, how would exercising help it? Walking doesn't do anything for your shoulders, that's the only exercising I know how to do. To bad I'm to lazy. Dog doesn't want to stay home alone, and she might not want to go either.

I'll get shoulder replacement surgery, if they'll keep me awake while they do it. So I can talk to the surgeon.