After Gastric Byp...?

It seems I have a possible food allergy? My face used to get extremely red and hot only after eating foods containing sugar forms. Now it seems, it's when I eat other foods. Example: I just ate a piece of Rotisserie chicken, small amount of Velveeta mac & cheese and some canned string beans. I know the rules of eating after byp but I was just wondering if it's possible I may have a food allergy? I'm three years out of surgery.