I apologize if I've mentioned this before and you've already tried it, but have you sprayed Bitter Apple on the area? I know that's one of the uses, to deter overgrooming.
Bitter apple is alcohol based, so it would sting. however petsmart carries another product called bitter yuck, it is made for use on wounds and plants. It's not alcohol based sneak shouldn't sting.Will the bitter apple sting if he has opened any skin??
Feliway doesn't work on these monsters.