Need help with Bangaii Cardinal

[Moogled]

Does anyone know what this disease is? It started when my water quality went down and the Bangaii had started out with a small scratch but it's been getting progressively worse.

So far I've tried to increase water changes, feed it chopped garlic with fish food, and removed my carbon. I don't know what this disease is but it seems to be some sort of fungal infection.

I took these pictures after the fish had settled in to "sleep."

Any help is appreciated.