My DD2 is like that. She's strawberry blond and fair skin. Her's flairs if she eats farm raised shrimp because wild caught doesn't do that to her. Wine also does it to her, maybe the sulfates? She has also self diagnosed (since childhood) egg white allergy and nut allergy, although she can have peanuts because it's a legume.

On your big flushes, it could be the rise and fall of BS because I think that is a real thing as the hormone insulin goes up and down.