Post your waterparameters and detailed description of how you are treating.
Generally I treat for ich with raised temp (86 deg F ), Formalin and Malachite green on days 1 , 3 , 6 and 10 - do 25-50% waterchanges just before the meds , don't feed and a large waterchange after the last med along with carbon filtration.
If you don't succeed it could be one of the following problems:
- too cold
- it may be velvet and not ick, if this is the case you want to treat the same way in addition to keeping the tank totally dark(covered) and treat for one whole month.
- worst case scenario is that it is a resistent strain of ick.