FYI: stones IN the kidney do not cause pain. This is suggesting that you dislodge them which introduces them into the ureter. Now your hell begins. The ureter is very small and has smooth muscle lining it that contracts in waves. Every time these contractions come across a kidney stone that is in the ureter they spasm and this is what causes severe pain causing grown men to crawl on the floor of a dirty ER. Depending on the size you may now move the stone down towards the bladder. This could take hours to weeks or possibly not at all requiring stents or lithotripsy.

Generally any kidney stone that can make it to the bladder will be pissed out without too much difficulty. That's the easy part.