Could be celery. Celery strings look exactly like they did when they went in. SO maybe fish it out unfurl it and have a look.

I have seen Celery strings in my stool also. They look different from candida.

If you saw a big amount if it though I would find it odd for it to be celery. Only you know how much you ate and what would be comparable.

I have no trouble with the shakes. What product are you using? I use Sonne's and it has not taste whatsoever and if I drink it immediately it is not even thick. The first time I thought it would come back up just because I drank down a large amount, But after a few minutes I was fine and within a day or two I no longer had that issue.

I would not use juice as the Sugar might feed it. It would seem you would have to add alot to get to taste like the juice.
I have seen concentrated Sugar free orange and lemon oils in the grocery store. Maybe a little lemon would work. Might be enough to change the taste. or try a different brand.

I think Colonix has a banana flavor. Maybe you could add some caprylic oil to that. It actually has alot of stuff in it already.

Michelle