sensitivity to hot cooked cereals

on behalf of a friend, i was wondering if anyone has experienced this or knows what may be the cause.

it started with oatmeal, and when my friend eats it, there is almost immediately severe stomach upset and nausea ... this is an adult male who only started having this problem about a year ago.  so recently, he tried cream of wheat instead and this time had the same reaction, to the point of vomiting.  this is not a time-delay like an allergy or food poisoning.  it is immediate.  but he does not have celiac disease or other sensitivities, eats wheat and oat bread products all the time.

is it perhaps something to do with cooking? some chemical reaction, or that it is just grain and no "buffering" agents ... (in the case of the oatmeal, this is rolled oats, not instant) ...

any help, or even a starting point to research this matter, would be appreciated.

hmm, idk, all ican say is thato atmeal is severely constipating for me while for everyone else it seems to have the opp effect?

Maybe it's a gluten sensitivity.