I would definitely get a second opinion. And I would see a gastroenterologist rather than a surgeon.
But meanwhile I would request a copy of the entire colonoscopy procedure including nurses' notes and anesthesia/sedation.
I would think it more likely that the fissure has something to do w/any sphincter muscle/nerve damage than a colonoscopy but you might just as well find out what if anything occurred during the scope.
I'd also be inclined to request a copy of the entire C-section delivery as well, again including nurses' notes, anesthesia, etc.