What Causes Abdominal Pain Post Gallbladder Removal Surgery?

My son had his gallbladder removed last year at the age of 27. His was only functioning at 7% but no stones. He had not been the same ever since. Has had a ct scan after surgery and no problems found. He eats very healthy since the surgery but now he doesn t hardly eat at all. He says his stomach hurts straight thru to his back and still has same symptoms he did before he had surgery. Everytime they draw blood his bilirubin comes back a little high. HIs sister has Gilbert s syndrome and I suspect he does too. The surgeon said he had genetically small ducts so could this be causing his stomach pain?