They could be impetigo. They also could be "fever blisters." I think your doc should consider doing sultures for both of these, and treating accordingly. If he's ever had the same thing before, in the same place, it's probably a cold sore or fever blieter, in which case, it will go away by itself. If he hasn't, or if you're not sure, you should check it out.
Best.
Dr. Rockoff