I remember with Mowgli that I'd take a rag and soak it good in hot water, then press it onto his chin for a bit, follow that up with hydrogen peroxide, and then another hot rag treatment. He absolutely hated it, and it took several weeks to get all the black crusties off, but it did (eventually) clear up. Also, if Allen's eating out of plastic bowls, switch him to metal or ceramic. That's all I know to do for kitty zits.