Bob,
Because you hadn't masturbated for two weeks at the time of your fall, this may have complicated your phimosis (foreskin not as stretched and flexible as usual) and caused some sort of related urinary effect, especially because you now only have normal urination only after masterbating. I suggest you make an appointment with your doctor to be examined and discuss possible injury or other complications that may have been caused by your fall.
Best of luck,
Maria