The bumps sound like hemorrhoids. If they are large enough they can theoretically make stool difficult to pass, especially if there is accompanying local inflammation.  Hemorrhoids are usually also associated with pain and/or itch and sometimes bleeding, so if those symptoms are also present then hemorrhoids are the likely culprit. That said, you may have more than one problem going on. Difficulty in passing stool can often be the result of stricture (narrowing) at the opening of the pouch.  I think it's advisable to schedule an appointment with your doctor to determine exactly what the cause is.  Luckily, if hemorrhoids and stricture are usually very manageable once properly identified and treated.