I don't actually think fecal exam is needed, what you described sounds like pinworms, you don't need exotic vet to get meds, same panacur is used for all round worms in other animals, any clinic will have it, you need to know the weight of a frog and they just need to calculate a proper dosage that they can easily check on spec vet website
you seem to miss the point that not only Shnookles but the other 2 have to treated as well, if they live together they all will have worms even if you don't see them.