
Well garlic fresh or in capsule form will help prevent flea bites as does brewers yeast, it is the vitamin b in the brewers yeast that prevents bites in people and animals :)
I'm not sure what you are describing is bites though, if the vets have prescribed medication for it?
Vitamin e really helps skin and coat, as does neem shampoo from: www.neemgenie.co.uk which will help keep skin and coat healthy and also if there is a problem with mites. They also have natural products to protect against tics too so might be worth a look on there.
I try only to use natural products for flea and worm prevention as I don't think chemicals administered either on the skin or taken orally are always a good thing.
I use neem shampoo on my boys about once a month at least in the shower, it smells lovlely and as I mentioned above protects against fleas and mites. They have vitamin c and e daily, plus brewers yeast, garlic and flax seed oil, they are also fed a raw diet.