Sorry to hear this, cav.
Melafix is pretty useless as far as treating anything so don't ever bother using it.
When dealing with fish illness the best practice is to consider treatment options slowly. Its important to try to ID the problem before jumping into action on treatment. I know that people feel the need to "do something fast" because their pet is ill. But for fish at least, unless you know what that something should be, its best to take sure steps to address a specific problem. Also, many hobbyists who may know specifics about a fish, are not necessarily the best choice for advise when it comes to diseases. Its not a favorite area to investigate for hobbyists but if you are going to keep fish, its a good idea to acquire that knowledge.