Can you explain that "enlarged" small intestine? Do you mean on gas presence inside the small intestines? Abdominal pain can be due to intestinal spasms caused by too much gas collected in the bowels.
CT-scan is not the best procedure for examining small intestines. Colonoscopy can't visualize the small intestines, too. It can enter only the large intestines up to ileo-cecal valve.
Small intestines can be visualized with contrast X-ray image (small bowel series), small intestine endoscopy (enteroscopy) and there is a new method called capsule endoscopy.
Did you have abdominal ultrasound to check the liver and gall bladder?