That said, it seems to be worse if he eat gluten, and if he eats too much not great food (at birthday parties), blue food colouring is odd too. I think he just has a sensitive gut which is easily overwhelmed by some foods and stress.
Has Hirschprung's disease been ruled out? I know of kids with similar symptoms who had short-segment Hirschprung's and were diagnosed very late. It is rare but might be worth considering.
My son has Hirschsprung's disease. While it is possible to be diagnosed later in life, it is really rare. The children who are diagnosed later are very sick, with lots of failure to thrive issues, multiple hospitalizations for serious conditions, etc. The top specialists in the country on Hirschsprung's disease will say that it is nearly impossible to not be diagnosed in infancy or during the first year of life given all that we know about it.
While you can certainly read about the disease and see if it fits, I would not go too far down this road unless your son shows the following symptoms: distended belly, chronic foul liquid stools alternating with constipation, failure to gain weight, stools that smell worse than any frat house, anemia.
I don't want to sound harsh or be taken the wrong way. I am just a mom who has seen too many people throw out Hirschsprung's as an explanation for constipation when in reality, kids are extremely sick if they have undiagnosed Hirschsprung's disease. I have seen too many moms worry unnecessarily.
