dog and cat itching on back

Question
We have two dogs and two cats. The dogs began itching and scratching, mainly above the tail area, this past late summer. We took them to the vet who said even though there are none or very few fleas visable, (we never saw any) that they are suffering from a reaction to the bites. He said it doesn't seem like an infestation in the house since we have not seen any, then he gave them some flea drops, sorry to say I don't recall the name of them. He said the cats are normally clean animals and will clean themselves. It is now Feb. and they are still scratching and digging in the area. The cats have little scabs at the top of their tails and are very anxious when they are touched there. It seems maybe like a skin rash that has been passed? Without going into more detail, the vet had put our one dog on Prednisone, then he got so sick he was close to being put down, and the vet could not explain why. Felt it was a wrong diagnose or something and didn't feel comfortable taking them back there. I have been trying OTC things like Hot-Spot treatments, etc. Any advice would be welcomed. Thank you. The poor little guys are going nuts!

Answer
If there is one flea, there are a hundred more.  Fleas can live in the house year-round and they can continually hatch because there aren't any chemicals that will kill the pupa stage.  Above the tail area is the exact area for flea bite dermatitis and they are probably hypersensitive now.  I would recommend using ADVANTAGE on each pet EVERY MONTH regardless if you see fleas or not.  You can try giving Benadryl to help for the itching....the dose is 1 mg per pound of weight twice a day.