If it is white spot, it should have been wiped out by now, assuming you used the correct dose of medication.
There were strains of white spot that could tolerate heat and Malachite Green but they aren't very common and normally heat will kill it. You might have a resistant strain, in which case you can either use Copper or move the fish to a different container each day for a week or two.
There are also strains that can remain dormant in aquariums without fish. If this happens you need to add a small amount of water from an aquarium with fish in, to the tank with no fish that has white spot. Do this each day for a week. The white spot parasites sense the fish chemicals in the water and come out of dormancy, and start looking for a host. But because there are no host fish in the tank, they then die off.