Most likely you got one or more small kidney stones, which are currently on the way down to your bladder and have hurt your ureter. This also explains the discomfort your experienced. Had the same ‘issue’ last year (also peeing blood & pain) and was scared at the beginning too. Go to a hospital and get an X-ray. The best I know is this regard is the Cathay General Hospital (國泰) in Taipei’s Renai Rd. The have an X-ray machine producing digital images (not slides, like the other hospitals), which can be magnified to see if stones are left in the kidney/s and if yes, how small or large they are. The first thing the doc most likely will give you is a medication to stop the internal bleeding plus another medication, which will relax your muscles so that you can pee out the stone. After a couple of days and some more pain you will be OK again. Keep in mind that you have to drink lots of water (3 to 5 liters per day) to ‘flush out’ the stone/s.
Here is another thread about the same subject: [url]Kidney stone/exercise problem