[LunarBerry]

I remember Brewer's yeast being a natural oral alternative. A recipe I once posted mentions mixing it with coconut oil as well and give it like a small treat. A ratio of something like 1 teaspoon of coconut oil with 1/2 teaspoon brewer's yeast. at that small age I'd give half a teaspoon of said mixture.
Revolution does have a flea med that's for puppies weighing 05.-5lbs vet had me use that one about as soon as I brought my girl in and she's used it since.