Hi Andy,
You'll be pleased you finally managed to discover the root of the problem, but no doubt you'll be apprehensive regarding the forth coming pain that has been mentioned.
I had a kidney stone and the pain was bad for sure, it lasted all morning, however as soon my doc gave me a pain killer via injection I was able to go back to work an hour later.
I was very fortunate in that the stone eventually came away of it's own accord and I never felt a thing. I just spotted what looked like a lump of brown sugar. Amazingly, after experiencing so much pain, I never felt a thing as it came away.
Though I didn't need it, I was told the hospital usually blast these stones into tiny fragments which allows them to pass naturally without pain.
I truly hope the same applies to you and all goes well for you and that any pain you do feel is as minimal as possible.
All the very best to you.
I'll be thinking of you.
willie.