first, you should know that ibs is the standard acronym for "irritable bowel syndrome."

what you are describing is a straightforward anxiety problem. non-pharmacological approaches would include practicing the situation until it becomes boring, meditation, yoga, cognitive behavioral therapy. the easiest and most useful [because it has other benefits] is practice. but you need to do that in as realistic a situation as possible. if you can, recruit a friend or friends to grill you, even deliberately try to trip you up. make it your game to look for any traps in the questions or tasks posed. repeat as often as necessary to feel very comfortable.