Cory skin peeling?

My wife has two bandit cories in her 10 gallon and we noticed one has what looks like a spot of skin that has peeled off just behind his left gill. He also has a whitish spot on top of his head that looks as if the skin is going to peel and I noticed the other cory is starting to get this same thing. I have been treating the tank with melafix because one of her dwarf gourami's had a small spot on his side that looked like an open wound. I finally removed them to my hospital tank which I just did a 100% waterchange, added some salt and a tablet of Maracyn that treats a symptom similar that says white or grey blotches on the skin. Has anyone ever seen this on their cories? do you know what it is and am I treating it correctly? Kyle

is white spot fatal to cories? can it be treated? what types of medication should I find? I havn't seen this listed on any of my stuff but I'll look harder. I may make a trip to petsmart today anyway so maybe they'll have something there. thanks, kYle