I can't believe this kind of neglect happened. Poor baby! With the mouth rot and RI, keep in mind that he may not be willing to eat. If he continues to ignore striking but willing to obviously acknowledge it, just continue to try as he gets better, or go back to the vet to see about other feeding options. Give that little guy plenty of love and affection, and please keep us updated. I also agree with Rich, if you have a copy of the paper work from the vet visit, a receipt showing date of purchase, and obviously you have the animal, go ahead and try to get the pet shop to pay the bills, if not file neglect charges against them.