If your cat is having spots or developed crusty scaly skin then it can be ringworms that have created this infection on it. It is a fungal disease. Treat it with Lime Sulfur dips, Itraconazole, Ringworm Vaccine, Miconazole and oral griseofulvin.is your cat itching also? If this is the case then there is Flea allergy dermatitis. Take it to vet because symptoms are indicating towards Ringworm disease.