My system must be a lot like Sherry's. I cannot tolerate fiberwhile flaring either. However, I do put Red Mill Ground Flaxseed Meal, 1 T, on my rice cereal and don't have a problem with it. I also have diverticulosis, so I try to eat fiber when not flaring.
As far as the white in the stool. I have that almost all the time. I always thought it looked like mucus to me. I still see a tad of blood from time to time but I think it is from my internal hemorrhoids. I am do for a colonoscopy soon. Had a sigmoidoscope the end of May, while beginning a flare and the doctor took biopsies, so hopefully, no cancer.