I was told the deep hip pain is caused by a deep spasm so close to the bone that you cannot see, but it is a spasm. Forget the technical name.
Metaxalone was prescribed for me and it helps about 80% of the pain.
I hope I answered your question, feel free to ping me if you have any more. I'm also in the MS community forum, and you can search Tysabri in the search field in that forum. We've had a ton of discussions on the drug.
:) Hope you feel better soon!