The vet gave him a dose of Revolution and said to let me know if things don't improve. Lilysmommy--his skin does look dry and has yellow skin flakes gathering. It sounds an awful lot like the same thing! If his skin doesn't improve with the Revolution I will have him checked for other types of skin infections. She looked at some of his quills under the scope, but didn't do an official skin scrape (the quills had the bulb on them, so she looked at that)
I am thinking I will give the Revolution a few days to work and keep a close eye on his skin/behavior in the meantime. It really is beginning to sound more like a skin infection than a mite problem though.