Thanks for all the great advice! I washed him with Dawn, and he hated every second of it. He kept looking at me like he was saying "but, we just did this yesterday, and I was good today and didn't even roll in the mud, and yet here we are, in the tub - AGAIN!" lol. Bedding is in the washer on hot (oh, please let it not ruin my new super soft sheets) and I've vacuumed. I'll go tomorrow and get advantage or frontline and some powder for the carpets. It's been about an hour since I bathed him and he hasn't scratched once since, so hopefully the Dawn killed whatever nasty critters were on him and now I'll just need to do a major clean up.
My poor boy.