One of the most important thing you can do is keep a food journal, its extremely beneficial at a time when one is experiencing a flare-up. You write down what time, where, and what you ate; how you felt before and after; Bowel Movements; and your Exercise.
There are plenty of templates online that you can download to help you.
with a food journal you can see what triggers and bothers you, and what is safe.
it has helped me a great deal, in identifying what’s good and bad for me.