Ok.......monitoring the situation over , maybe a period of weeks or months may well provide you with a diagnosis, BUT from what you have said my first thought would be that it was a kidney stone passing from the kidney, down the ureter and for a few hours " got stuck." This is not an uncommon situation and the history that she gave via you, is quite typical. There may or may not be another stone, which may oy may not pass into the ureter which may or may not get stuck. A lot of "mays " there.
If it were me, i would not consult a medic at this stage, but if she does, then keep us updated.