You have a shoulder problem. Maybe you shouldn't have an Apple Watch. I would hate for it cause you any additional problems. Yes I know you really like this watch. But maybe try it on the other hand.
Here's another link.
http://forums.macrumors.com/threads/apple-watch-causing-slight-pain-in-arm.1880533/
I do have shoulder issue. But just using my phone all day bugs me so I'm not sure if the watch will make it any worse than playing on my iPhone all day.