What makes you think your gecko needs to be de-wormed?
Typically when an animal has an intestinal parasite they eat and eat and eat trying to curb their hunger, and you can actually see the parasites/eggs for the most part. I really don't think your gecko has the nematodes that panacur will kill.
From my experience blood in the stool is rarely a parasite problem untill the animal is so far infested that you can SEE THE PARASITES in the fecal matter. You absolutely need to take the gecko to a vet, in the condition you describe the panacur could do more harm than good.