What Causes Blood In Urine After Sex?

I been having blood on my urine after sex,I have has cat scan, endoscopy, etc.,no answers where do the blood comes from,during the endoscopy , the doctor say that I have some white cells inside my penis, , plus he says that i have a lump on my prostate, and something about the uretra, he wants to do a biopsy on the prostate, and check the uretra, so far no explanation about the blood on my urine

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69 years old, 5.11