Hello Thanks for posting query on Healthcare Magic Pain on left side of flank can be due to many reasons CT scan abdomen is good tool for evaluation but it can not answer all type of pain abdomen that’s true and same has been told to you. It definitely rules out some diseases (serious) of abdomen. CT gives very little information about muscular pain and no information regarding pain originate from heart Some stones in gall bladder are not visible in CT scan but can be seen in ultrasound. You yourself try to characterize pain and try to find out aggravating and relieving factors, associated factor (injury, twisting, bending) or other symptom. Based upon all detail discuss with treating doctor. Do blood invesigations as advised. To relive pain continue painkiller under follow up with doctor Hope this helps, wish you best health Dr Jeetendra Sharma Senior Consultant Critical care Medicine