Please help me

My family has no history of kidney stones. I don't eat salty and I am healthy. I don't over eat anything. I didn't have a problem with my kidneys till this years semester. I am 19 years old and my first kidney stone was 4mm and now for one month I am trying to make my second kidney stone fall. First one was at right. Second one is 2mm and right. But it didn't move too much although I drink at least 2-3 Litres of water and walk 8-10k. Doctor said my right kidney have got bigger and if my kidney function test is bad then he needs to make an operation. And one month ago everything was clear and this 2 mm one was the last one. But now I have a new one on my left and even doctor couldn't understand. I took voltaren pills one week much but once for three days and twice for four days. I am so scared. I don't want to have kidney failure. I don't want to die.