I had bad stomach problems since I was in my early twenties. Gas, reflux, indigestion you name it. Found out I had AS at 47. Stopped eating starch and have not had any stomach problems, not even the need for a rolaid (which did more harm than good). Changing my eating habits was the hardest thing I have ever done, but it is the best thing I have ever done. Wish I would have done it twenty years ago. I look at it as a lifestyle change not a diet. Good luck, the people on here are the best. I would not have made it without them. Feel free to have your son email or pm me, I will gladly answer any questions. It sounds like he is where I was at his age.
Darrel.