I successfully brought a few fish back from this stage, although only one lived to tell the tale past a few months after coming back. My solution is kinda crazy and not recommended, but what do you have to lose?
Nuke the tank. Change the water, then...Maracyn, Kanaplex, Sulfadiazole, tea tree, you name it, hit it with max doses all in one shot. Hit the tank with heavy doses of a quick start solution too...your likely to nuke your biofilter in addition to the infection, got to keep that bacteria and in this case its only going to be found in a bottle. You have nothing to lose.
If you don't see progress though in a few days, or see a worsening past a day, you know what the right thing to do is?
Edit: Disclaimer: If you read my posts, I have a reputation for relying heavily on meds. Its your choice to go against the status quo and follow me on this one. Most intellegent fish keepers would say this is a very, very bad idea. I don't disagree, but it works for me because good healthy water is just not enough for my luck.
