I went to the doctors on sat (july29) the doctor than told me she thinks I have a kidney stone. My left side hurts and my lower back. thats why she thinks I have them. But I was wondering how do you know for sure if you have them? What kind of test do they do to see if you have them? I need some help ASAP, as I will be going to the doctors again tomorrow.

A CAT scan should give you an affirmative diagnosis. Many stones will not show up on an X-ray.