What does it mean in medical terms if you had horrendous side pain and urinated blood for a while?

STRAUSSIAN - Your description fits well with the ping of a small kidney stone through the ureter on its way to the bladder and out. Along the ping, the stone probably crumbled into small grains which ped more easily. The blood comes from the sharp edges of the small stone scraping the delicate inside lining of the ureter. Such pain can be very severe and require immediate relief. If anything like that happens again, be sure to strain all your urine through a piece of fine mesh gauze and save (dry) anything that even looks like sand which you would then take to your doctor for a lab ysis of the stone. People who p such stones tend to have repeat episodes. Often the right set of x-rays will show more calcium carbonate type stones in the pelvis (belly) of the kidney on the side of the pain.