both my parents have had colonoscopies, and neither one had a
problem with them n*-wise, they just said it was uncomfortable to use a
laxative. if you're worried about feeling n* maybe because of the
anesthesia, request an anti-emetic. i'd definitely recommend the
colonoscopy as it's better to be safe than sorry. sometimes my stools
are very thin, usually when they're a bit softer (sorry if that's TMI),
which makes sense. hope you're feeling better!