That doesn't look like a flea bite. I too think you should take your dog to the vet as you have no idea and no one here does really. I'd hate you to be 'treating' for one thing and it turned out to be something else.

When I posted photos of Pereg's spots I was also advised to take her to the vet, so I did.

Back in the 1980's I had a Cavalier dog with a very similar looking rash. My vet diagnosed it as acne, and prescribed routine cleansing and a tapering course of low dose prednisolone tablets, which were to be given early in the morning, so as not to interfere with his natural hormone production. He thought that Geordie would grow out of it as his hormone levels settled, and true enough I never needed to take him back for further treatment. Don't know whether the same applies for bitches though.

You took your dog to the vet! That's what's being advised here. Cavvies are a bit notorious for having sensitive skin.