i feel pelvic pain after i masturbate once in a month. i have thick fluid of sperm. during ejaculation, when i am going to finish, i screamed and my pelvic muscle pushed that cause many problems like i can walk for some time. well, i have no blood in my ejaculation.
Get your semen examined. There may be some infection in prostate or seminal vesicle. Pain is due to muscle contraction and spasm.