Thanks for the resources. I'll be doing some more research on the nematodes; the gecko thing makes a lot of sense, though. The book wasn't clear on whether nematodes were seen more in wc specimens or not. He did say that he had subocs who were treated, then tested negative for nematodes, then were later positive for them even though they hadn't been in contact with any other snakes, and recommends "regular deworming." Hmm.
I just texted the rabbit rescue owner and she says she has a ton of Panacur that I can use. The dosing and frequency for Panacur is even in the suboc book, so I'm comfortable administering it. I was planning to just wait till mid-to-late next week to give him the medication though (and weigh him to determine how much). Is it better to give him a week to settle in first? I would think that is best, because whatever he has is probably not super new (if it was anything more than a weird poo) and he hasn't visibly deteriorated from it?
I also just texted the seller and will see if he's had any recent treatments. I also asked if he was on mice because I think I read somewhere that rats can cause a sort of "fatty" poop, but maybe I misremembered that.