I had been a vegetarian for years...and I still got them regularly. Many things cause kidney stones, excess calcium, acid (this is from meat), magnesium/ammonia, and there are rare kidney stones made of cystine.
Unless you know which type you have, you don't know how to prevent them. The most common is calci kidney stone (calcium). Only a doctor can tell you which you have an how to prevent them.
I pass kidney stones at least twice a week. I don't even go to the doctor anymore. I simply pee in the hat the doctor gave me and strain them through the mesh strainer he gave me. (It's not a real hat, it's one of those things that looks like a puritan hat that sits on the rim of the toilet...the nurses called it a hat.) I put it in a specimen cup and take it the doc's...they give me a new specimen cup and the process starts over.
Sadly, none of the diets I have tried work. I gone vegan, vegetarian, cut back on my calcium intake...nothing works. I'm prone to kidney stones and I have narcotics if the pain gets to bad. If I don't pee for 18-24 hours, then I go to the hospital and they break them up so I can pass them. I had an MRI done several weeks ago to check the tumor on my adrenal gland and they found 22 kidney stones on the one side alone.
Just keep drinking the water...but add some lemon to it. That always always always helps me. Something in the lemon makes them easier to pass.
*hugs*