Search the forum, there is a lot of people here who think stomach issues are related to AS ++. I think one of the causes of AS is in the stomach, after the pain I had disappeared when I cut gluten and focused on healing my stomach.. The average Western diet of grains, high carbohydrate/starch, sugar, additives, and dead processed food is not made for us. Some are also sensitive to other things, like cow's baby's (not grown up humans') milk as well.

I haven't had stomach issues as serious as yours. At the age of 13, I had to see a Gastroenterologist. Have had trouble ever since.  I have been gluten free for 4 years. It helps tremendously. I think i cannot stop taking the Aciphex because of my sulfasalizine. Which is my miracle drug. I knew when I took my first dose, it worked. I also drink 1 dark beverage a day(usually crystal light peach tea. I drink Water the rest of the time. It is manageable.