First of all are you sure that you don't have a flea issue. Sometimes fleas are very hard to see so I would check for that first. I would also suggest that the vet run a general test panel to check for things like a thyroid issue. If it is food allergies then you should check the ingredient list in your regular food and try a new food that has different ingredients. It would be helpful if you could list for us the ingredients in both your original food and the new stuff. The vet stuff is usually not very high quality (lots of grains). I would also suggest adding a little salmon oil to his food which may help with the dry skin. If he still seems really itchy then take him back to the vet and get a cortisone shot which should give him some relief for about a month or so. You can also call your vet about advice on allergy meds which can also be used short term.
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