Pimafix and Melafix are snake oil. I know some very experienced folks swear by them, but I've never seen them work on a fish that was actually sick.. There's a fish veterinarian somewhere in Rockville (quick google search will find her) if you want to go that route, but she tends to have a long waiting list. His fins don't look fine to me - they are cloudy and I see a white spot on the tail. My guess is he's got some sort of internal infection stressing him that's opened the door to skin infections. If he's eating, try a food with metronidazole and praziquantel (Beantown Aquatics makes one). You could give him a round of General Cure, as well (it's Metro and Prazi) before starting the food.
I wish you luck.
