You have all good advice so far. If sugar is a problem switch to pedialyte (I like the unflavored) to keep you hydrated and energetic. Try a liquid diet (but make sure you get enough protein, fat, sugar, and vitamens) for a few days before you go. Ask your doc for an anti-anxiety med (I like .25 xanax) to keep your stomach calm during those times one would normally be nervous (take off and landing for example.) I am going to DC for a wedding and I might take one the morning before if I know I will be driving in traffic sans potty. I would also bring along whatever butt comforts you regulary use at home. I always bring wipes, hydrocortizone cream, and epsom salts. If you bring the salts get the really small container that looks like a mini milk carton from CVS. That way they won't spill and look like drugs in your suitcase lol. Next I would pick up whatever you can always eat (for me balance bars and ramen noodles) and bring those with you too. If you dont feel up to eating with your group just order tea (or whatever you can drink) and eat your balance bar after. I also really like the idea of bathroom scoping. It will probably be hard to do before you leave. Remember that your hotel probably has a bathroom in the lobby in addition to in your room. If someone from your group is showering and you have to go head to the lobby, or the pool, or gym, or bar in your hotel. You should find a bathroom there.
When I was in Spain all the resturants and cafe's had bathrooms and I would just buy a bottle of water and ask to use el bano. Look up how to ask for the restroom in Italian. Make sure you have some small change with you (in euros). Again, when I was in more rural parts of Spain we had to bribe people to let us use their restroom but they never said no once we offered a buck or two. Finally, remember that people are more afraid and less grossed out by vomit than diarrhea for some reason. If you need the restroom in an emergency you can run in and ask for the bathroom motioning to your mouth like you are going to vomit. I think you would get ushered in right away. You could look up the Italian word for car sick. That may be more embarassing than telling someone you have to poop lol.
In American cities sometimes I will just walk in and say "I really don't feel well, may I please use your restroom." Or, if there is a female matri-d Ill imply that I just got my period...(without grossly saying that.) When someone hesitate once when I asked for the bathroom I just whispered surprise female issue and she said oooohhhh go right ahead. So be creative, learn a few phrases, bring your comforts... oh I also have a microwave heating pad I bring places. Lots of hotel lobbies have hot water for tea that I use for my ramen and a microwave I use for my heating pad.
Finally, I believe Italy has siesta (nap time) just like Spain. Mid afternoon EVERYTHING closes. That is probably not the time for you to be out and about walking around and a great opportunity to take a nap just like the natives!!! Do the things you are comfortable with and come up with some back up plans for yourself when people want to go somewhere you arent comfortable. As long as they know you are happy doing something fun they won't mind going on without you and you wont feel like you are holding them back or end up being miserable because you forced yourself to go along.
I hope you find a way to have fun!!!
1 more thing... I just checked your meds and you are just on Pentasa? What about trying entocort or prednizone to get you through? Entocort really helped me!!
26 Year old married female. Diagnosed w/ CD 3 years ago, IBS for over 10 years before that, which was probably the CD. Currently on Pentasa 4 pills/4x day, hysociamine prn, nexium, and ortho evra. Good times!!!