D.
Dear N.,
Go to the health food store and read books about digestion. There are a couple of things that will help; probiotics (they are beneficial bacteria that get wiped out by drugs, antibiotics, etc) these are essential for good digestion. Also get enzymes and these can be gotten in chewable form. Papaya enzymes, and there are other enzymes. You might want to try cutting back on any dairy. Use almond milk and other stuff besides milk and cheese which are very binding.
Find a good chiropractor that is good with kids. There is one in Tarpon Springs Fl. Alton Gustafson. Or get referrals.
That is what I know about digestion.
D.