My Archibald has a ras or something? It's only this one round spot, I have no idea where it came from.Nothing has changed around the house, nor in his routine. No new food or litter or grooming things. I'm nervous, has anyone had this experience? If so what is it? Will it go away on it's own or is there something I can do to help? This isn't the best image, but I tried. Please and thank you for your help!