My advice is to go to the restroom if you have the urge and your situation will allow it. Waiting will only make your feelings worse. Whenever away from home, make note of restroom locations ahead of time wherever you are, in case you have need for one. If you have been diagnosed with IBS, has your doctor prescribed a digestive relaxant such as Bentyl?
have u tried anti-spasmatics for this -u could talk to your doc about it --or ear smaller meals low in fats so instead of 3 big meals eat 6 through out the day.