white patches on Bala

Question
I have a bala who has developed "mutton chops", white, oval, cottony patches on either side, just behind his gills.  He's had them for about 3 months, now.  I've used Wal-Mart's fungus treatment, Marcyn-2, and am now finishing up a 5-day course of ampicillin, and he's still in need of "shave".  He's eating, swimming and behaving normally, and the pleco who shares his tank seems un-affected, but we'd like to add additional fish the tank!  What can we do???

Answer
That is a fungus in it's later stages. If you don't treat it, it will kill the fish.
Best not to get new fish since some fungus's release spores.
I would try some Fungus remover that comes from an actual pet store. You would have better luck but it sounds pretty far already.