Shooting Pain In Right Shoulders, Arm And Fingers. Hurts While Moving In Certain Way. Is It Pinched Nerve?

I developed some pain in my right shoulder that shoots down my arm into my fingers. It seemed to be related to how I was sleeping with my nursing infant. I stopped sleeping that way and the pain eventually went away. Then, I napped on my couch a couple days ago and woke up with the same pain in my shoulder, but rather severe. It hurt constantly and hurt very badly to move it in certain ways (e.g. couldn't lift it all the way up, extended it right or left hurts alot). I just thought it was a pinched nerve and would go away. Then yesterday, after sweeping and pushing a stroller, my arm and entire shoulder area are in great pain. I almost can't use that arm at all. Wondering what is wrong??