Urethral trauma resulting in Hematuria (blood in the urine) is possible from bicycling and there are any number documented medical cases. I have no idea as to how common. I'm sure there are lots of other things that can cause it as well, many of which are more serious than bruising your johnson. GO SEE A DOCTOR. Rule out the bad stuff, correct the problem if it is your seat or position, and continue on. Lots of us ride many miles without having such a problem, so if the cause is related to your bicycling it should be pretty easy to cure.