Welcome to my world. That is exactly what happens to me. It's not bad enough that we have GAD but why not throw in a little IBS just to make life more interesting. I have two methods for dealing with the added annoyance, 1) Before I know I am going to be in a very stressful situation or going out for a meal (which is a high anxiety thing for me to do), I take an Imodium...that is a precautionary measure; 2) This is something I have just discovered...calcium carbonate. If you take something like Caltrate with vitamin D which is like a chewable toffee easily carried in you purse, before or during a meal or even with a piece of toast, it sees to help with the diarrhea. Make sure you don't take the calcium carbonate with magnesium which it often comes with because too much magnesium will create more diarrhea. I think it is ok to have some magnesium but not a lot if you've got this problem. Of course, now I am going to mention, the book Eating For IBS, I'm starting think I should get royalties for mentioning this book so much, anyway it is an easy read and full of tips and recipes for digestive help for people like you and me.
Let me know if you try any of this stuff and/or your results.
Absolutely, I have never suffered with IBS until I started with the anxiety, sometimes its so uncomfortable and I have found it was worse eating Weet-Bix breakfast cereal. I take a natural product called Mintec one of the main ingredients is peppermint oil, it helps me.