Poll on ages 23-28 and stomach issues?

I have been finding more and more people in the age group 23-28 who have odd stomach issues. Can only eat certain foods without getting nauseas or having severe cramps or diarrhea issues. Has anyone else out there these ages had these issues? Im trying to do some research as to what vaccines everyone had during those times or even the diet provided by the school systems to see if it has something to do with it…