Similar situation here — had 1st colonoscopy at about 55 and just had second one at 70. Nothing deemed "wrong" either time except that now, at 70, I was told I have a redundant or tortuous colon. Who knew? I thought this was a congenital and rare condition, not something somehow acquired over the years. Interesting that you, too, seem to have 'acquired' the tortuous colon. What is going on?
My problem is that suddenly, months ago, I started having constipation, like I had as a youngster, so I had the 2nd colonoscopy to see if there was a problem. But, like you, I can have 'normal' BMs too. Trouble is, I get "backed up" and then have the opposite problem: huge loose BMs accompanied by loads of lower region cramping/pain. Not fun.
I don't remember this happening since those episodes of more than 35 years ago. I'm seeing the GI doc this week but I'm sure he will say it's IBS and throw Miralax packets at me. I also have GERD so feel like I've got double-trouble.
Oh, and my gall bladder was removed in '04 due to horrible pain attacks and 'sludge,' not stones, but I never got the post-cholecystectomy 'dumping' (frequent diarrhea) syndrome that so many experience after that surgery. I have heard that many years later problems crop up for some people for the first time. Perhaps I'm one of those people and will now be plagued with this into old age.
Hope you are feeling better and have gotten some answers to your own questions.