acne
I had the same problem with Cyrus, He looked like he had little pimples on his chin( I always thought he was going thru puberty). At the time I worked for a Verterinarian, I took him to work like normal, and had her look at him. We washed it up real good with Chlorhexiderm soap and changed his bowls to Staniless steal. I also kept a package of Stridex acne pads at home to wipe it from time to time. It woprked great and they went away. You can get a bottle of the soap from your Veterinarian, you may already have some from a cut paw or some other accident they seems to get into.