If the dry patches are eczema or psoriasis-like, then yes it can be food related. For years, on and off, I would get eczema (didn't know what it was at the time) on the back of my neck. Finally not until this year did I connect it to the times when my sugar intake increased.
I'm doing an elimination diet right now, and was fine until about 4-5 days after eating soy and got a bit of psoriasis type dry skin on my neck and arm.
With DS, he had bad cradle cap, eczema spots, red ring rash (burn rash around anus), mucousy poohs, lots of poohs, and productive toots. These were all signs that is body was rejecting the wheat and trying to get it out. Remember, the skin is the largest organ so the body will also try to purge toxins/rejects out through the skin.
Head on over to the Allergy forum!