I recently had sex with my girlfriend and my sperm was full of blood. later i had to urinate however there was no blood in the urine. what is wrong ?

Hematospermia: Occasional blood in semen (hematospermia) is pretty common and usually not serious. Many cases result from minor injury to the prostate or seminal vesicles e.g. bicycling, horseback riding, etc. If the blood clears up in the next few ejaculations (it can take a while) and doesn't recur, all is well. If other symptoms, e.g. urinary pain, penile discharge, or it continues or recurs, see a doctor.