It does sound like you are having a flare and rebif is not meant to improve your pain.

What you are describing sounds like MS hug. If you search it, there are alot of posts on it. Steroids may help you improve if you are having a flare and a medication such as baclofen, neurontin, or zanaflex may help a bit with the pain.

I have had the same problems with my back and rib cage ever since I was first dx. It is worse sometimes than others and can really painful. Hope you can get some reflief soon. Sometimes an ice pack helps me cope a bit with the pain. Others find heat is helpful to a degree.