You might try regular intake of aloe vera juice or DGL (a form of licorice), and maybe see someone who knows homeopathic medicine or just buy a diarrhea remedy. I just get this when I have to do something particularly anxiety producing, but most of us with anxiety have some kind of digestive upset. I think these natural remedies can help. Digestive enzymes also help. Also, try to see if certain foods make it worse and stop eating them. Of course, the only cure is to cure the anxiety.
Oh yes... the dreaded stomach problems (or what my friends and I call "intestinal peril'). This is a classic symptom of anxiety. I rarely have trouble with this now that I am being treated for anxiety (and depression), but I went about a year in college thinking I had stomach or intestinal cancer because it got so bad sometimes. Exercise, and eating more fruits and vegetables, helped a bit. I also remember drinking peppermint tea and ginger tea - these helped with the aches and churning. My friend (also an anxiety sufferer) had some good results with that Activia yogurt.. but after about a month, the results were "too good" and she was using the toilet 5 - 6 times a day. It sounds like you could benefit from techniques that will calm you all together (like exercise, meditation, deep breathing etc). You can find info about these online, but your doctor should also be a good source on info.
I have randomly occurring symptoms I mean;) it appears I accidently left out "have"