You don't mention seeing a gastroenterologist. You need to see one and get a colonoscopy, especially at your age with your history. Now that you've recovered from your surgery, it's time to get invlolved with your GI again, and you are due for a colonoscopy. This way he can view the lower bowel and see if anything is going on.
what happens though; if you have seen a gastenerologist and had every single test known to man or woman; they find nothing; and your still in constant pain and think you may have issues with your stool. Ive seeked 2nd and 3rd opinons and still nothing. so I don't know