Poor boy. How is he now? Any improvement? I'd vote for a dose of strong antibiotics also, and possibly surgery. Hydrogen peroxide is good for open wounds and will help clear away the dead and sloughy tissue.
I love apple cider vinegar for infections like this as it kills bacteria on contact, but if there is an open wound/ulcer, don't use it directly on the area as it is acetic acid and will sting like crazy. Keep mixing it in with his diet preferably food though, one good teaspoon full every day
