What other fish diseases display white specks on fish aside from ich?

I have a tank of fish that have been healthy for ages, and anytime in the past I have cured quickly the ich disease from my fish if it was ever displayed, but recently I got 2 convicts from an Earl May that had ich, figuring I would treat it before it spread.... well.... it spread and now I have been treating them fully for over a week and the fish are just getting sicker and sicker, the Firemouths are doused in the white specks, why, if it is ich, are they not being cured? And if not ich, what else could it possibly be? I fear my fish may not last another week, so an quick information would be appreciated.