Fungus can take awhile to treat. I have also used betadine to treat fungus on my dogs face. My rooster used to get a few of those white spots in his pea comb, and I would use the miconazole or clotrimazole when I remembered. It kind of went away for a long time, and then I would see it faintly...
It could be a very mild case of favus. It could be short lived. I saw that occasionally on my pea combed rooster, but it did not get bad. I would not go to a vet for that, but if you want to treat it with a little miconazole or monistat cream daily, that might be good. You could also try...