It took me 4 different urologists to properly diagnose this. I had it for YEARS. Every single time it happened I thought I was going to die. The only thing I could do was lay down on a hard flat surface (usually the floor wherever I happened to be at that time) and just let it pass with lots of heavy breathing and silent crying. I basically was immobile, couldn't even move without getting super light headed and felt like passing out.
Once I finally found a dr that properly diagnosed it, he taught me the open book trick and MY GOD what a difference. He is also the same one that did the surgery, and it's been many years now without an instance. Life changing.