My balls hurt and when i masterbated blood was mixed with my cum. why is that? is this normal?

Could : Could be an infection. You should be examined by a physician and have your urine checked.

Blood : Blood in the ejaculate is most commonly associated with prostatitis, a prostate infection. Please see your physician, who can further evaluate you, and if appropriate prescribe a course of antibiotics which can cure your problem. Best wishes.