I had two. My first indication of a problem was pink urine. That will get your attention. Went to the doctor and confirmed not UTI, so that was out. Eventually went to the urologist and his immediate diagnosis was kidney stone. Confirmed with MRI. Still had to get scoped (nothing like paying a few thousand dollars for an office visit where I get raped up the urethra…). Also found out via MRI and confirmed via the scope that I have an enlarged prostate. Ugh. Got the Flomax treatment (still taking it, does help a bit to more completely empty the bladder). Finally passed one of the stones (so proud, my wife and I high-fived…it’s the little things that count when you get older). It was about the size of a fat grain of rice. The other is still in there AFAIK. Not causing any problems (knock wood, cross fingers). I only had one morning of mild lower back pain, out doing the weekly food shopping and feeling bad, like I pulled a muscle in my lower back and could not work it out or relieve the pain by adjusting position. Got home and took some pain medication and laid down and the pain receded. I have heard a lot of bad things from other people about the ultrasound procedure to break up stones, probably best to avoid it if there is any chance of passing the stone.
Good luck and best wishes. BTW, do like the Flomax, it's kinda like a poor man's Cialis or Viagra...which is at least a nice benefit. I don't take it every day, usually every other day. Getting old sucks and part of the cost is resigning yourself to getting up in the night.
Oh, yes, and do drink plenty of water. I still don't really drink enough.