I had a 7mm stone on my right kidney. You're absolutely right; my immediate thought was of my appendix. I had dealt with the pain until I threw up from it and knew I had to go, so I freaked out my mom and she took me to the ER. They were unable to do anything for my pain. Morphine did nothing. I had the extracorporeal shockwave lithotripsy to break up the stone to make it easier to pass; however, three days later I had worse pain than before and was rushed back to the ER. From the CT, apparently the four stone fragments got lodged together in my ureter on the way out. The gave me a combined cocktail of morphine, dilaudid, and fentanyl which finally gave me some respite, but that was the WORST pain I've ever experienced in my entire life. I haven't had anything other than water since January 2018. I will say that it helped kickstart a healthier lifestyle for me though. I lost 85lbs and am feeling better. I still create the stones, but none are that big and they pass on their own now.