I'm sorry to hear about your loss, but that was one *very* sick fish.
Sometimes it's possible to diagnose and treat illness in a fish early on, but in the advanced stages like that sometimes there's just nothing you can do. If your fish is very obviously in a lot of pain and isn't responding to treatment, sometimes it's better to euthanize them than to let them suffer. Here's an article on how to humanely euthanize a fish, if you are ever in a situation like that again:
http://www.fishforum.com/tropical-fi...nize-fish-698/