Hi John. I've used levamisole, both the sheep oblet 'Tramisol' and in Disco-med (ingr levamisole and piperazine). Dosage I've used is 200mg/10 gals for 24 hours then water change. There's some info here,
http://www.thekrib.com/Diseases/nematodes.html, search the posts. Some swear by it. I had some luck with it, they recommend one treatment, I found treating every second day for 5 worked better.
As far as discomed, I've fed that.
Barb