By any chance are you embarrassed by your homebrew? JK! Google alcohol flush. I have no idea why it would only happen with your beer. In the end, it's not harmful, not an allergy. Just a genetic deficiency of an enzyme. Hope this helps.
It might be an allergy, or you might have red mans syndrome. That is a simple niacin reaction from the niacin released by the yeast. I would have it checked, but if its red mans its not harmful, you just look sunburned, its called flushing.