This could be an allergy to fleas, or pollens, or food, or it could be a problem with mange mites, or ring worm, or if any of those flakes move it could be lice, and it could be a generalized staph infection from the dog scratching at an itchy problem that is now a full blown skin disease.
The right treatment depends on the right diagnosis. Your best bet to get that is to go to a vet for the diagnosis and the meds. If you are not sure your regular vet can help there are veterinary dermatologists or allergists who may be able to give a more expert diagnosis and treatment plan.
You can read about itchy skin disorders in dogs here to see if you can figure out what the problem is before you see the vet
http://www.all-creatures.com/456008.html
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