Need help ID and treat the disease ulcers on my poor clown fish

[Puffer]

Hi guys, I have been away for a while. I need help ID and treat what ever is inflicting my clown fish. Here is a few pics of the pink fleshy ulcer looking skin lesions on the clown fish. Can someone ID what it is and how should I treat it? I tried both hyposalinity and Instant Ocean's Lifeguard (Haloshield), and it did not work at all.

 

[MRichardson]

is your ammonia or nitrite high?
what does he have for tank mates?