I agree with belleenstein. Keep a food journal. You may discover a pattern, like that your disease flares 2 days after eating food x. If possible, an elimination diet is quite helpful. Start with a handful of basic foods you know you tolerate, then add one new food every few days. It's a good way to pin down exactly what does/doesn't agree with you.
In regards to SCD, you don't have to eat fiber if you don't tolerate it. Same goes for fat or anything else that disagrees with you. What works for one person on SCD may not work for another. If you take a look at the BTVC yahoo group, you'll find that some people's diets vary wildly with one another. It's recommended that you start out with cooked, peeled, and deseeded fruits and veggies. Applesauce, pear sauce, pureed squash, well-cooked zuchinni are all good for starters. If you absolutely can't tolerate any fruits or veggies, stick to the other legal foods on the diet (meat, homemade yogurt, eggs, etc.). With some time, you more than likely will start to tolerate things that once bothered you.
Good luck with whichever diet approach you decide to go with! Hope you find something that works for you :)
34 years old, Crohn's disease for 15 of them
Current Meds: Humira since 7/08, Pentasa, Effexor XR
Supplements: 3 kinds of Fish Oil, Multi-Vitamin, B-Complex, Vitamins D, E, & K, Calcium, Magnesium, Enzymes
SCD since 12/01/08 - eating Stage 3 foods