My mouse has a severe infection, Help!?

My cat managed to topple the tank over a while back and got in a good few nips before we were able to come to the little gals rescue. THis was About 3 months ago. I cleaned the wounds up and kept an eye on things and for a while it;s been fine, but now all of a sudden she's picking at it to the point where there's almost no fur on her back anymore, just a raw pink bloody mess! I can;t get her to stop picking at it, and Ive tried disinfecting the area but she goes right on back to trying to basically skin herself alive. Is there anything I can do about this? Most vets in my area don't even take small white mice (they're clified as 'exotic' for some reason), so I don't know if there's anything I should do. Should I simply prepare for the worst at this point? :(