When I was a child just in grammer school, I use to get a really bad stomach ache before school (I was always picked on and not part of the peer group) and every time I would have to sit on the toilet for sometimes what seemed like hours. Later on in life as it never went away, I went and had a colonoscopy which was then diagnosed as spastic colon. All due to stress and anxiety. I too have suffered from aniety all my life. As I got older the diagnosis of spastic colon went into colitis which I still have. There are medications out there, but I choose not to take them because of the high narcotic effect it has on you. It has belladona and phenobarbital in it. Called "Donnatol". Been on that many times and can be very addicting. So I opted not to take it anymore. The only thing I don't like about having this, is alot of times it comes without warning and I can't go out anywhere for fear of a blow out. In fact, it just happened last week and had it for two days straight.
So, you are not alone at all. It has everything to do with Stress and Anxiety. Unless. you dig deeper and doctor finds something else is an issue.
Good luck and I know you will do just fine.