Well CT scans don't really show much when it comes to Chrons. I have chrons and it never showed up in the CT scan. My GI had to do a colonoscopy (turned up negative) and then had to do an endoscopy to look at my small intestine which was positive for chrons. So have him do an endoscopy instead. It's not as invasive or as terrible as a colonoscopy, I promise.
I find that the medicine dicyclomine helps with mild pain and if pain gets severe it helps to completely clear out (like colonoscopy prep) and stay on a liquid diet for a few days. Heating pads help tremendously with the discomfort as well!!!
Try seeking out free clinics which may have arrangements with imaging facilities to do free or discounted imaging. If unsuccessful, explore cheaper more basic imaging tests such as fluoroscopic upper gastrointestinal series and small bowel series, which are not as good as CT but better than nothing.