G'day Bus
Had 3 colonoscopies and 2 gastroscopies done over the last 15 years.
Both done at the same time for convenience whilst under a twilight anesthesia so couldn't remember anything. Took about 25 mins. for both procedures with no ill aftereffects other than a a slightly sore throat for a couple of hours.
Just do it, it's the most definitive way to diagnose GI issues.