I'm going to make the kind of statement I used to snort at, but I no longer believe that anything can be separated out as just in the mind or just in the body. Even a broken bone, to use an example which is so obviously a "body" problem, still affects your mind. You'd still be upset about breaking it, your brain has processed all of these pain signals, and is relearning to do everyday activities while your arm is in a sling, etc.
So, I think yes, all of those things you cite may have affected your gut, and by the same token, the fact that you have IBS, could be contributing to your "stressing out" more often. It could be that a drastic change to either the stress or your gut would also affect the other. I imagine that if I were sure of my ability to digest just about anything, I wouldn't be the nervous wreck that I often am!
Ladies & gentlemen take my advice, pull down your pants and slide on the ice.