D-mannose has been a god send to me when I have had a bladder infection. I find it is as good as pyridium for the pain (I have had a lot of UTI's) and it gets rid of the infection at the same time. It is a highly concentrated form of the Sugar found in cranberries so it's really pretty harmless. It prevents the bacteria from sticking to the wall of the bladder/urethra and is naturally found in the kidney. I buy mine at Vitamin Cottage or Whole Foods. I take three or four pills every couple of hours or there are instructions for dosing the powder form here or there are many other websites with good info.
With that said you obviously have a more serious infection than a UTI so probably a good idea to follow up with a doctor especially if it's a stone but maybe something to give you some relief in the meantime.