Hopefully it is something else, and not really the
Tysabri. Has this happened every time you have had an
infusion? You mentioned you were on antibiotics - if you've been sick or had an infection of some sort, that could definitely be a big part of how you are feeling. I know the longer I'm on Tysabri, it seems I get sick easier - and when I do, it hits harder and lasts longer than it used to.