Hmm. That's good that it's starting to get better, what ever it is.
Make sure you take the carbon out of your filter (if you run it) while running the medicine's course, or else the carbon will take the medicine out of the water.
If its ich, or at least you think it is, you need to wait til the ich falls off the fish, then swims around looking for a host before the medicine will work. Maybe in a day or two, take all the decor and substrate out and rinse it in scalding/boiling water. Itll disinfect it. Do it for a few days.
If not ich, then I wouldnt know what to do/how to treat it :c