Hello @supercalifragilistic and welcome to Mayo Clinic Connect. As you may know, Connect is not a place where you can get a medical diagnosis. We are patients like yourself who share our own experiences and health journeys. Have you addressed these questions with your doctor?
There are many reasons for stomach pain like you describe including median arcurate ligament syndrome (a rare disorder that is often overlooked), gall bladder problems, etc. You do say that you have had "an ileostomy for UC" so I would assume you have had other GI problems before. What has your GI doctor said about this new discomfort you are experiencing?
I'm just wondering: Is there a reason for your fear of pancreatic cancer? Have you had family members affected by this type of cancer?