By the way, you might want to start him on a little yogurt if you are doing antibiotics. Antibiotics kill all bacteria, good and bad, and yogurt introduces the "good" bacteria back into the intestines. You can find some plain yogurt that is not sweetened and has real culture in it. Or even better, you can try adding a probiotic to the diet, if he'll be on antibiotics for a while. They have the same thing as yogurt but in a larger form. Here's some more information about probiotics and they might even be able to help with skin problems.
Probiotics, What Are They? Do our dogs NEED Them?