Cocker with bumps/scabs

Ollie our Dane used to get exactly what you are describing.  Spent more than enough money on antibiotics and other medicines for him that would clear it up but only while he was on the medicine. The time in between the medicine kept getting shorter, so we could see we were fighting a loosing battle.  They said it was a staph infection.  Basically its allergies and he had an weakened immune system that we believe was caused by vaccinations.   Eventually we took him to a skin specialist and he was found to be allergic to dust and grass--two things that we can do nothing about. He was put on weekly allergen shots and he is fine now.
Good luck to you and I hope you get on top of it before spending too much money.  It really concerns me that I keep reading more and more of this kind of thing in dogs.