Thank you for your thoughtful response and encouragement. Your experience is very validating.
I plan to keep flushing. I can still feel more congestion in there.
Thanks for the heads up about the black or red stones... that might have been disturbing to find if I didn't know what to expect!
I also think I saw some kind of "eggs" coming out in the stones once. They looked like gooey shells that had been opened, and the stones were formed around the walls.