Hi - My 7 year old, Sonny has this scaly, flaky yellow skin condition over most of his body. I just noticed on his underside, this black discoloration on the skin, that can be loosened. It is right at the base of the fur strands. It covers one-third of his underside. Sonny is borderline hypothyroid, and is on a low dose of thyroid medication. Could this have anything to do with his skin condition? Does anybody know what this is, and how I would treat it. Thank you. Susan