I would probably call your nurse/doctor and ask about this. I get tenderness with Betaseron occassionally too, but never that bad. It just gets tender to the touch and itches.. usually when I get a red welt or bruise.. my legs are the worst for that. I also have to be careful not to inject near where clothes rub, like the waistband area.
Diagnosed with MS April 2006
Longstanding anxiety and depression
Currently on Betaseron