does it look like he might have just scratched himself too hard?
if they don't go away in the next day or two, or if you see anymore spots like those, i'd take him to the vet
to save from having to pay for the visit just take him to get his claws clipped and casually ask the vet to take a look (a good vet will happily oblige and would examine the ears, teeth, etc. anyway)
then if it's something parasitic they'll prescribe you something on the spot - it may be as easy as just putting ointment on the sores