Good to hear there's a diagnoses. Yes, I'd say he stopped croaking due to parasites, but I'm far from an expert so I can't confirm for sure. Is he looking very skinny? I'd suggest whenever you find him not looking so good, to give him a Pedialyte soak; 1:10 ratio of Pedialyte to de-chlorinated, lukewarm water. It will replace lost electrolytes and give him a little more energy, which I assume he doesn't have much of because he's not eating much.

How big is he? Is he big enough to force feed if you need to?

Hope that Panacur kicks in soon...