Both my DH and I have very similar conditions. DH became ill during a camping holiday. Fortunately we know how to deal with it but it was really stressful.
I have twice been admitted to hospital, not realising I was ill. If it weren't for my DH knowing I wasn't well I wouldn't be here to tell the tale.
That said, we still go on holiday; recently drove to Switzerland.
Just be sure that you and your DH eat the right things, drink plenty of clear fluids, not alcohol, and that he stays regular.
Check out local pharmacy, doctors, walk in clinics and A&E. If you have everything to hand you won't need it.
It's a bind but try not to stress as he will stress and that can make his condition flare up.
Have a nice holiday.