Wondering if their food is making them itch!!

Our boys have been on a reletively cheap dog food for the last 2 or 2 1/2 months.

The last couple of weeks we have had very itchy dogs, it started when they caugh fleas from my brothers puppy, which isnt uncommon I know. We treated them for those, which got rid of them, a week later they started itching again, but I could see any fleas, but we treated them again, which didnt stop the itching.

They are both itching their back, round their tails, tummies and thier crotch area, Simbas got brown staining around his crotch from constantly licking and biting himself.

We were about ready to take them to the vets or de-flea them again, but its just occured to me, could it be their food???

Flint used to be on wainwrights, and never had problems with it, but since we moved they have been on FAB, which is from just for pets shop.
They both really like it, which is why we got it for them as Flint can be a little picky.

Can it take 2 months for a reaction to become apparent?

Im wondering wether to try them on wainwrights again :S

same thing with Bentley. He is now on James wellbeloved but originally was on Science Plan and he had little pink areas and he was scratching and his poo was too soft and not expressing his anal glands. I then changed him to Fish4Dogs and he improved in less than a week. Unfortunately I bought a huge bag and let the air get to it so he went off it. I can't recommend it enough.
I'm no expert but I would suggest the food could be the issue, maybe check with your vet?

My 2 had been on 'working' dog food for a few years, and seemed to get progressively itchier...

Murphy had visible dandruff for several months

I swapped them onto Arden Grange (Large Breed) and within about a month and a half, the visible dandruff was gone, and neither seems to be even half as itchy. They do have their moments though!

I'm sure that the cheaper food I was using was contributing to their itchy feeling...