Pain Near Right Scapula?

I get a pain sometimes on the right side of my upper back. It feels like it is under my shoulder blade or something and it hurts to take a deep breath. I can breathe through my nose, but when I get this pain, I don't seem to get enough oxygen that way, so I need to take deep breaths which just results in more pain. I have tried to massage it and lie on my other side, but nothing seems to help. It usually stays around for a few days before it goes away, but it almost always comes back. I haven't had it in a while, but it's back again now, and hurts badly. I don't think it's a torn muscle or anything, because I haven't really done anything that would cause that recently.

If anyone can help, I would greatly appreciate it.