Hi Annabella
Mrs Robert123 has Crohn's disease (very similar condition) which is now thankfully in remission, I have asked her advice,
1. Relax as tension and stress can make things worse, I remember the first holiday we went on, just prior she had had a very bad flare up, on holiday she felt as fit as a fiddle, she put it down to relaxation and no stress
2. Watch what you eat and drink, avoid ice, although different foods upset different people there is no set rule of what is in or out
3. Always make sure you are near or know where the nearest toilets are
4. Take your medication (in your hand luggage)
5. Make sure the people you are with know about your condition and needs
6. You a person with a condition not a condition with a person, it awful put you can get over it Mrs Robert123 went through some terrible times but is determined to get on with her life and has a good career lives life to the full and enjoys herself, if you need anymore advice please feel free to PM me (it's not the easiest illness to talk about, for some other advice please go to
http://www.nacc.org.uk a great site that will help you a lot (get the can't wait card)