Really bad scabbing, any advice?

I have two cats that we believe to be tabby/abyssinians. I've had them for about two years now, and they've both been wonderful and generally healthy. However, My one kitty, Watson, has had skin problems pretty much since I first got him. First he just had some tiny little scabs/tiny scab flakes on his chin. It went away after a little while, but then he started scabbing again and it went from his chin to all over (mostly on his chin, neck, and tail) I brought him to the vet and they explained it was more or less an allergic reaction, more than likely to a flea bite, but his brother, our dog and my sister's cat were fine (no excessive itching, reactions, or sign of fleas) they gave him a shot which helped the scabbing clear up and his itching to cease and gave me some flea prevention.
Since then he has been alright, but the scabbing and itching has started suddenly again. We've moved and have been living in our current house for about six months and was okay for the first four or five months. There's been no sign of itching/scabbing on his brother or our pitbull, and only the occasional moth or other common bug in the house.
Ultimately, I'm on a tight budget and want to do whatever I can to help him and his itching/scabbing subside without possibly making it worse or having to bring him back and forth to the vet. Is there anything that could at least help his itchiness that can help him from digging at himself so much?

Hi there!

My cat didn't experience exactly what yours is going through (she gave herself a dry bald patch from excessively rubbing up against a broken venetian blind to get into the window to see outside...what a weirdo, we had to get curtains, lol) BUT to alleviate some of the dryness/itchiness I would suggest a hydrocortisone spray. I got a bottle of it at WalMart for a few dollars and it comes in a decent amount. I sprayed that on her and after we had discovered it was the blinds, switched to the curtains, and sprayed her with that for several days, the dryness cleared up and her fur grew back (eventually)

She's a black cat so it looked DAMN SILLY on her 

Anyway, they would have this at most pet stores I believe, chain stores or privately owned, WalMart is just closest to me and I imagine it would be a little cheaper there, and don't I know how money is always an issue! We want to care for our babies, but breaking the bank doing so is another monster in itself....Oh, it also has a 'distasteful' taste to it so they don't lick it off so it can heal.

Let me know if that helps!