If you check out the internet for raw food, you will find lots of info on feeding puppies and dogs that way; dogs can have more grains than cats. This should help your little guy. We fed our cats that way for over a year and it really helped them. I took a detour and now have to get it going again. It is definitely better for them, their general health and their beautiful coats.
They get the enzymes which they need from the raw food. There should be lots of info on ringworm, etc., but I would think that this problem would clear up with the raw food.