Is it more to one side or the other? Or right along your spine? Do you ever have an itchy feeling that seems to kind of "float" around in the same general area? There's a nerve that runs around from your spine to your side, I forget what it's called, and if it's being irritated it can cause these symptoms, as well as the breathing issues. When mine is unhappy you can literally feel the ball of tension just under my shoulderblade.

Try an ice pack on your back and neck and see if it helps any! Sometimes yoga stretches are helpful too. So sorry you're having to deal with this!