Thought I'd offer what I've experienced...wife suffered for almost 3 weeks with the same type of pain below her left shoulder blade, finally went in, Doctor palpatated the area to find out exactly where the pain was, went out and consulted with a couple of other Docs, came back in and said they were all in agreement that it was something that could be completely remedied by one cortisone injection in the correct location....we agreed to try, he came back in about 2 minutes later with a needle and injected directly into the pain area. She looked at me about 4 minutes later, just after the Doc had left the room after giving her advice about follow-up and said, "I can't believe it, it's disappearing..."
Been pain-free ever since...