Sick African Dwarf Frog

[Fishyfish1]

Hi everyone!
I have a tank that has a fun little ADF in it. I've had him for a few months and he had been completely fine until a couple of days ago. He seems to have lost most of his appetite as he hasn't been eating well the past couple days, but he seems to be as active as he usually is. When I went to feed him today I noticed a white spot on the tip of his nose and redness around his little face. My water levels all tested okay but I'm not sure what's wrong with the little guy. Does anyone know what it could be/what I can do to treat him? I did move him into a quarantine tank after I noticed the spot today and all the other residents in the tank look okay.

 

[evil Nick]

it almost looks like a puss filled bruise. They jab forward pretty fast when going after food. is there anything in the tank he could have bashed?
Most you can do is the usual, keep the water clean, very clean. Could try some melafix