At least, it looks like a hot spot. I just found it. I cleaned the spot, and used some stuff called Magic Skin that I got from our old vet for Mouse when she had some skin issues. I am going to try to take care of this myself, but if it doesn't start to improve in a day or two, he will have to go to the vet. I dread this, because I worry that he will blame the raw diet.
He does have a habit of scratching his back on the underside of one of our chairs. Is it possible that he just rubbed a raw place? I haven't seen any signs of fleas, but I guess it might be time to put some Advantage on him, just in case, but I can't do it until this spot heals up, as it is too close to the application site.