[M] [43] Question about Kidney Stone Stent

Greetings.

I am a 43 year old male. I do not smoke, though I do drink, but not heavily. I stopped drinking whiskey, and now only drink beer once a week. I am trying to eat healthier (holy moly it's expensive). I suffer from a rare autoimmune disease, Sarcoidosis, but that is not the issue this post is about, just giving some background medical history.

I have recently been having trouble with kidney stones. First episode was roughly three to four months ago. I've just been hit with them again. First time was a 5mm stone in the left kidney, now its a 6mm stone in the right kidney. The urologist was unable to laser this stone, as it is too far up in the kidney.

My question is this; what causes the intense pain in the kidney when urinating? Yes, I have a stent. The burning I at the end of the urethra in the penis I can deal with, but the pain in the kidney while urinating is almost unbearable. If I wait even a bit to long to urinate, it's like very intense cramps. When I do urinate, when I begin I get a slight cramp like pain, then while I am finishing, the cramping pain in the kidney makes me want to vomit it's so bad.

Just want to understand what causes this pain. I have a theory, but I am no doctor.

Thank you in advance for any help.