The answer is different for everyone.
To figure out what makes you feel worse, do some detective work.
For several weeks, keep a diary of what you eat and when you have flares. Then look for patterns. Avoid things that seem to cause cramps or a trip to the bathroom. See if your symptoms get better or go away.
Talk to your doctor about what you notice. Your goal should be to eat as many types of healthy foods as you can, so your diet is as balanced as possible.