...can present as low back pain. What you describe however is a little atypical. Usually the renal pain is one side or the other. Also, usually the pain will vary through the day, hitting and letting go repeatedly. None of this is hard and fast however.
Does the pain radiate to the tip of your wiener? Does it hurt to pee or does peeing affect the pain at all? Is your urine dark? Any associated nausea or vomiting? Does the pain get worse when you tap on the kidney area?
I could go on but you get the idea. One last thing, a urine that tests negative for blood does NOT rule out a kidney stone.
I'm glad you're cutting back on the drinking. Tell your family hello for me.