Why do I have so many kidney stones? I'm sry it's so long?

3 Fridays ago I woke up at 3am and felt sick to my stomach but we had an appointment that I couldn't miss. So I went to that after the appointment I told my mom my right side hurt we thought it was appendicitis but we went to the ER and they said that I had a kidney stone on both sides and that it would pass in a couple of days. Well 7 days later they didn't pass so we went to the urologist and he said I have 5 kidney stones on my left and 4 on my right. I drink a lot of water too so my mom and I were shocked. So now I have a ureteral stent in to open up my ureter so they can take the kidney stones out. Then two weeks after that there doing the right side. This hole stupid process is taking six weeks of my summer away. How am I going to prevent them and why do I have so many I've never had them before and I'm only 14