I just thought of something else. If I remember correct, you said that after the Doc removed the cath you did pee a stream but it stopped. When I had stones, I would start to pee and then it would stop. The stone slid into my opening. When I used a intermittent cath I would push the stone back up and would drain through the cath. Next time I would go on my own and then stop. The stone slid back into my urethra.
Just a thought,