It's unfortunate that you had a reaction to the psyllium/benonite mixture. Nothing will work for everyone, and it's important that we all share our stories here to help others.
I have never used PB shakes and I passed mucoid plaque with my first (only so far) master cleanse. I didn't use any bowel products at all. Perhaps what you were passing wasn't mucoid plaque; as your doc said. That doesn't mean everyone else isn't passing it. You are unique and your body obviously didn't respond well to what you did. I know many people who do a Bowel Cleanse aren't trying to get rid of mucoid plaque; many pass thick rubbery old feces with all the shapes and bumps of the colon in addition to mucus and plaque or whatever. regaininghealthnaturally.com has good pics posted of some of these. I'm looking forward to a Bowel Cleanse this winter, as my Master-Cleanse revealed that I have A LOT of nasty stuff in there!
Let's keep the tone peaceful here, everyone. We're here to learn.