All Chrohn's, UC, or any other autoimmune issue needs to be tested for sensitivity to gluten. Even if it comes back negative, I recommend a trial of gluten free, dairy free, soy free and corn free.
My son had diarrhea for 3 months, they tried to tell us it was IBS. I said keep testing and sure enough his TTG transglutamase came back positive which points to celiac.
After being gluten and soy free for 3 weeks that cleared up. I continue to battle other issues, dairy and corn related, so now those are gone. Reflux being a big one, but slowly he is getting back to normal.
GL