Brief Answer:
May be from various causes

Detailed Answer:
Hi
Thanks for your query.

I understand your concerns. But you have not provided any details regarding your symptoms, like for how long, how many episodes, any associated symptoms, etc. There are various causes of blood in semen, like urine infection, prostate infection, prostate enlargement, prostate cancer, etc. We need to investigate accordingly.

First step is an urology consult and examination. Based upon the findings, further evaluation may include urine analysis and culture, semen analysis and culture, transrectal ultrasound, serum PSA, etc. Based upon the cause, exact treatment can be initiated.

Hope this helps.
Regards

---