I took a peek at this site because I've experienced the same thing and wanted to see what others have said. Yet I have done something in the past that worked. The trouble is that I got overconfident and went back to my old ways.
What I did last time that worked was to eat a diet of ONLY vegatables and meat. Breakfast? An egg and a plate of broccoli. Lunch? A piece of chicken and a plate of green peas. Supper? Well, you get the idea.
I remember clearly feeling like I could breathe again when I did this. My stomach seemed somehow calmer too. At the moment it feels tight and going to the bathroom only helps it to subside a bit.
The one problem that I did have with this approach was that I dropped a ton of weight. A had lots of energy and felt great but I wasn't eating enough calories. I started adding brown rice drizzled with olive oil to my diet and that helped me put back some weight.
Stay clear of alcohol and coffee, as well as sugary foods. Take vitamin supplements (but don't exceed the recommended dose). Get a juicer and juice some carrots or cucumbers to get enzymes into your system. Also, consider taking over the counter digestive enzymes with your food.
Anxiety I think it part of this but it is indeed cyclical as well. If you eat foods that will give your stomach a break (unlike junk food that wreaks havoc on your body) you will feel more at ease which will in turn help you to be more relaxed. Do some yoga - get yourself a video and do it for a while. It does help. Watch funny movies and shows. Stare at the ceiling and smile (this is a physiology trick for putting yourself into a good mood). And make sure to exercise. Your body is more likely to eliminate waste and toxins if you get some exercise.
That's all I've got. Hope that helps some of you out there. I'm trying to get back into this routine myself.