Pain during ejaculation and blood in the sperm can indicate a possible organic disorder located somewhere in the male’s genital tract. The male genital tract includes the urethra, seminal vesicles, paraurthral glands, prostate, seminal dusts, epididymis and testicles. Organic disorders can be caused by infections or tumors. Several diagnostic procedures including a physical examination, ultrasound and spermogram must be performed in order to diagnose the problem. You should visit an urologist immediately.