Sorry to hear about your kidney stones
My son started having problems with kidney stones at the age of 8!! His nephrologist said that it's quite rare for someone that young to have stones and that he was probably born with the problem. Even as a baby, his pediatrician thought he was having continuous kidney infections (incorrect); didn't even consider stones since it's so unusual at that age.
His stones were caused from a lack of citrate and he was prescribed a supplement and told to drink a LOT of water. He had to see the doctor often, bring in 24 hour urine tests and had many ultrasounds. Apparently, these things didn't work that well, as he continued to develop stones and still has them occasionally (He's now 21.)
He had the first of his 2 "stone-smashing" sessions (E.S.W.L.) when he was 8. Like you, he had the burn marks on his back. In his case, it was in both kidneys so he had 2 of them. It worked great, though! A few years later, he was back in to get more stones broken up. This time, it didn't work as well as he had a large stone pass naturally (painfully) after the procedure that was either missed or hit and moved away from the target. He was also given a strainer and we had to strain the urine and bring back anything that didn't pass through the strainer to our next appointment. We followed the instructions, so I don't know what happens if you don't.
We eventually stopped going to the doctor since nothing much had changed for him and he stopped taking the supplement. No matter how much water he drank and even with the supplement, he was still getting stones. The doctor did tell him, though, that if he ever gets severe kidney pain that he should get himself to an E.R. as soon as possible. That would mean that his ureter is blocked and the urine is not getting through. Then he would probably need surgery.
He still passes stones (probably will for the rest of his life), although they have come out naturally. According to him, it's painful but bearable and it usually doesn't last more than a day or two. We hope that he continues to pass little ones and that he won't get a blockage and have to go to the E.R.
So, I guess, going by my son's situation...if you start getting stones, there's a good chance you will continue to do so. I hope that's not the case for you, though. Hopefully this helps a little