Hm, honestly surprised loose stools would warrant a colonoscopy. That's not really that common to have for this type of issue that I'm aware of. But I do want to tell you about the newest and easiest thing to do which is cologuard. It's an easy way to get results that are similar to a colonoscopy. You get the kit at home, put the lining in your toilet and go. Pull the lining out, put some drops in it and send off to the lab. It's 95% accurate! Only down side is if they do suspect something, you have to have the regular colonoscopy. But it is less invasive and less money than the traditional colonoscopy and would imagine you'd be a great candidate if they push you need that. So, to me, this makes sense that you have loose stools during a stressful time. I often do as well. Important to just increase your water intake for hydration. I eat something like a spinach salad and it helps. Have you tried a probiotic? Those are very helpful also.
I'm not sure about the pelvic floor correlation. But your doctor has made it so if I were you, I'd investigate how to improve that. Two things that come to mind are visiting a physical therapist that specializes in pelvic floor strengthening. Yes, they exist. You could also try on your own yoga that targets that area. If you put that into your search engine, you will get lots of results from videos to watch to learn how or follow along or just instructions.