I FINALLY got the all clear from the latest stool sample yesterday! Phew, finally. 4 doses of Panacur (but really only 2, because the first 2 didn't really get in him), 3 vet visits, 3 stool samples, and LOTS of tank cleaning later and we are good to go. Luckily, the vet only charged me for meds when he administered them.
At least I know its not worth trying to give him meds at home now... the only way meds got in him was with a tube...
Also, I recommend if anyone has this problem in the future, throw away all the filter media in your canister filter and replace it with cheap filter material that you don't mind discarding. That way, you can clean everything a few times and not waste a bunch of money on filter material every time. The tank will just have to re cycle.
I added sand today, and Sedge immediately started munching on it. On to new problems
!