Hi Evar,
I think you & your daughter should get a second & 3rd opinion if you think its needed.
I too have a very long torturous colon and had a very large obstruction which sits very high up in the area above my splenic flexure are. The obstruction which was recently blasted apart by compressed air whilst undergoing a colonoscopy. Seeing it happening on the screen took sure took some processing as there were masses of tightly, flattened, square segments of black and red tissue flying apart at great speed.

There are a lot of problem areas in my colon but having the obstruction blasted apart had eased my mid- upper back pain considerably for about two weeks.
My sigmoid is riddled with large open mouthed diverticular along with smaller diverticular. My small intestines have fallen or been pulled down through 30 yrs of acute constipation & are all bunched up & causing nasty sharp pain at the top of my vagina and deep dull pain in my rectum area and I need to lean forward to pee! The red hot, sharp pain from my severely damaged sigmoid is off the charts when I defecate. For the past 3 years I have need to defecate standing in the shower - very demoralising😢 its a very lengthy process taking up to two+ hrs sometimes then I need to take morphine and rest for the afternoon.
The colonoscopy shows such thickened walls throughout the descending colon that only pencil thin, or self induced diarrhoea (which is how I've been managing it for quite a few yrs now,) can get through it.

For a few weeks I had such relief of most back pain since that darned large gnarly obstruction was blasted apart a month ago, but the excess colon has felt like a python in there & has wound its way back to the splenic flexure but is positioned differently and digging into my lungs again. I've also developed a row of small eruptions on my skin above the line of the descending colon - I'm thinking they can only be from the inflammation of my colon.
I'm going to a GP on Thursday so will get her to check them.
Bowel problems are the absolute pitts and having to explain to people why u can't confirm outings is so embarrassing.

Do think about getting another opinion. You might need to do. Bowel transit study - they're cheap and easy to do and s much can be learnt from them.
Wishing u all the best 💞💞