I think sugar would make me break out in a cold sweat now, too, after a few months away from it. Funny how you get used to feeling that way and you think it's normal, till it's gone for a while.

I ate tomatos for years and then one day I realized they were causing the cold sores I'd never had before. Don't eat tomatos, no cold sores. Don't know what made that happen, that year, but I do remember my great aunt was the same--only I only knew her after the allergy/sensitivity kicked in.