I'm very sorry to what happened to your baby! I have a Cat that came from an abused shelter with cigarette burns all over her and all that stuff.
She may be like YorkieRose said above, jumping back in fear, nervousness because she remembers what happened to her. I really hate seeing my doggies in pain.
I know it can be very costly to bring to the vet, but I think the medication will help her feel better and she should be able to get back to her usual self. and in due time won't be so nervous/jumpy i hope
best wishes to you and yours.