try putting honey on toast and sprinkling it with cinnamon and have your son eat that. It helps a number of things from digestive to heart disease. It is cheap, simple, and very effective in studies. I have done a ton of research on it and have found all kinds of success stories with the combination of honey and cinnamon. It's amazing.
I have suffered from chronic diarreah for over 4 years and I just ran across this information recently. Since I tried it I have not had any tummy trouble at all!!! I hope it helps your son. It's all natural so it can't harm him.
(raw or 100% pure honey is generally hypoallergenic) Ask a health food store employee if you have questions about allergies.
There is a 'type' of correlation if you look at people who have IBS and interstitial cystitis. for some reason many who are finally found to have IBS also experience misery with I.C. and it seems as if when one gets worse the other does also.
I'm not sure what gastric problems your son has, and what testing he has had done, or what you've found works or doesn't work, but has anyone suggested that relationship?