Check with all the vets in your area. Fecal flotations are the same with a leopard gecko as with a 100lb dog. They all use a small sample and look for floating parasite eggs. They may just be looking for some different eggs, so you could help them out by ordering a copy of Dr. Klingenberg's 'Understanding Reptile Parasites' book, and his laminated ID sheet with formulary. BUT, any good vet should have the references to make an ID, especially since many(most?) of the same parasites affect geckos as other pets. He should have the medications on hand and be able to calculate the correct dosage from the above references.
Good luck
Herpcam's Geckos
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Rob Jenkins
herpcam.com