Barium enema and tortuous colon

Curious as to how much a colon can change from year to year.  Had a successful colonoscopy seven years ago with some polyps removed.  Had another yesterday and apparently they could only get part way through because I now have a "narrow, tortuous colon" and a barium enema is recommended.  This really doesn't make me happy since the prep for a colonoscopy is bad enough but we do what we have to.  Does the colon twist with age and on its own?  This was the same doctor who is really a master at doing these so I'm confident he was being cautious.
Also--is any sedation allowed during a barium enema and, truthfully, aside from the awkwardness, how much actual "pain" is there?