Can a child be allergic to pop? My 7yr. old gets pop as a treat when we eat out.  Diet or regular.  He always gets a stomach ache.  While eating he had to use the bathroom.  After eating he said his stomach hurts & felt like throwing up, turned pale, shivers, gets hot, had RED blotches on both sides of his face & chest.  He doesn't want me to talk to him when this is going on.  It passes in a couple of minutes.  Then he says he is fine.  He always has stomach aches at his belly button.  I told his new doctor & he said oh it is constipation.  But I forgot to mention these episodes.  He has been on clonidine since June for ADHD & to help him sleep.  Is pop causing this? Had constipation when younger & now he goes so big it will plug up the toilet.  Don't think he had these episodes before the clonidine but yes on stomach aches & the episodes only seem to be when eating out.

Summarized question: Does pop cause any allergy in children?