I used to have ich many years ago when I purchased fish from a shop without checking other inhabitants of the tank.
The cure is not meds because they actually effect your fish and some discolour everything in the tank, its heat!
As mentioned the temp should be raised to 30-32c no higher, because you start losing oxygen retaining ability of the water
and will stress your fish.
If you look up the life cycle of ich on the computer, you can judge when its time to return to normal temps.
I have learned this information over the last 50 years thru books and by using the info myself.
I do not have diseases in any of my 60 aquariums.
Dave