Hello Soccer Mom,
It is very unusual for a patient to have Whipple surgery for colon cancer; this surgery is normally done for pancreatic cancer. Are you certain he had the Whipple?
Is he still being treated for cancer? If not, has his doctor given you any cause for his pain? I suggest you have a very frank discussion with his doctor about the reason for his pain and how to deal with it. He should not have to live with pain..
The bathroom issues are not that unusual for colon cancer patients. Many of them never get back to their pre-surgery normal but do learn after a while how to live with their new reality. A different sort of diet along with Metamucil or Lomotil is often very helpful. Has your father seen a nutritionist who might be able to give him some help along these lines? This might be an area to pursue.
Good luck with finding some relief for your fathere.
Joan L