Interesting, I am having similar problems to yours lately and also similar suspicions.
I did once the liver and gallbladder flush (with epsom salt, grapefruit and olive oil). I don't know what to think, it is certainly invasive. I am not sure it's safe, for someone who is not stable health wise. It felt like it was messing with the microbiome, I don't know. You do end up expelling a lot of what looks like gallstones. I guess only an ultrasound prior and post the cleanse could tell. I read extensively on internet about
it, there are many testimonies of people saving their gallbladder this way. There are also those who claim that the stuff that is expelled is really just that olive oil mixed with bile.
That said, once I was through with it, I was certain I would never do it again, it is very uncomfortable, you get nauseated etc, but here I am toying with the idea again.
After the cleanse I did feel lighter, better (but my general health was at such a low point at the time that this didn't make such significant difference) but I also felt that it wiped out my microbiota, although I felt this way after an enema too, so it just may be my subjective impression.
Dr Berg on Youtube has some helpful videos on the stomac-gallbladder-pancreas issues and how to deal with them.
I never looked into TUDCA, will do now. Also I have no idea what brand to consider, as I am aware amazon reviews can be misleading.
A few days ago I realized my recurring diarrhea could be due to xanthan gum in the bread. A while ago I started making my own gluten-free sourdough bread, and eating more of it than I would if it was store bought, but I am fairly certain now that I react badly to xanthan gum. It is a "largely indigestible polysaccharide" as Chris Kresser says. Just thought I'd mention this, although if you've been gluten free for so long you are probably familiar with this. I didn't like the stuff since I saw it, it's just so processed and I have always been very sensitive to foods, no wonder I am reacting. I should just go back to an occasional "polystyrene" rice cracker ;)
Here is a short interesting article on potential complications from xanthan gum https://www.celiac.com/articles.html/could-xanthan-gum-sensitivity-be-complicating-your-celiac-disease-recovery-r1360/