Posted 6/26/2014 10:47 PM (GMT -5)
One thing that may help is some kind of anti-diarrheal medication. You cant take these long term and you need to talk to your GI before trying them, but they do work for some people (including myself) and may provide you the short term relief you need for the trip.
Other than that, there are a ton of meds you can try (mostly enemas for the urgency), but the best thing you can do if these fail is to just be prepared. Carry a small bag with a change of clothes and some wipes/toilet paper, try to scout ahead to find washrooms, etc.