Thanks for your query.
Noted the history and understood your concerns.
Rectal cancer surgery
wherein a large part of the rectum is removed there can be altered motion habits.
But if a large part of the colon is still maintained that is not removed, the bowel movements should have been normal.
This means that there is most probably other problems that may be affecting and causing IBS like picture.
IBS means irritable bowel syndrome
but to say this to be IBS we need the basic investigations to be absolutely normal viz tests of stool, blood, colonoscopy
, CT scan of abdomen.
If anything is found during investigations it will be treated accordingly and if all the tests are normal get treated this to be IBS which helps a lot to have normal bowel movements.
Also watch for the intolerance to certain foods and beverages ans stolp anything that causes you the problems.
Control of the psychological effect of being suffered from cancer also can be a reason and an appropriate counselling
and medications may help.