I just had an idea. When the horses get an abcess in their foot, I rub ichthammol ointment on it; its a drawing salve and works great. But man is it nasty stuff. I wonder if you rubbed just a smidge on his comb, if theyd taste it and go yuck and leave him alone?
Cyn, you said you saw "one of the girls".....why not put him back, when he's healed a bit, and see who the girl is who's chewing on him and remove HER, not him?