Are you taking any medications, either prescription or OTC that contain
niacin?
Niacin can cause flushing which happens when our blood vessels expand (which
niacin is used for) and the blood rises closer to our skin which can cause really intense sensations of heat, extreme itching and a deep red "flush" of color to our skin which is usually limited to the upper portion of our bodies...........chest, neck, arms and head.
I'm afraid that pretty much sums up my guesses.