Sick Fish (Black Molly)

Well a few days ago I realised that my black molly is really ill. A week or so back it started to swim in circles, like doing a full circle, which I thought was odd. Now it's got a really horrbile white spot (Ulcer?) on it's back, and just lays at the bottom with big buldged out eyes!

It's in a tank on its own so nothing spreads etc. How could I treat this?

Could well be, I'll give it a go

Well after trying "treatments" it's getting worse, its now a lot fatter, more white things that look like peeling scales and just can't swim very good and not much at all. Eyes really buldged out. Sounds like Dropsy to me? ~ Low chance of survival?

It seems really unfair letting it live like this, could be anything wrong with it!

Any suggestions please.