Hello and thanks for the question
Most likely there is a slight amount of blood in the semen. Blood in the semen is called hemospermia. It is a relatively uncommon condition but can obviously cause alarm. Many times the cause for blood in the semen is never determined. However, there are some causes which can be diagnosed. For example, an inflammation or infection in the prostate can cause hemospermia. There can be an infection in the urethra, which is the passage that carries urine through the penis. There can be an infection or inflammation of the collecting tubes around the testicles that store semen. Also cancer or tumors can cause hemospermia as can medications that cause thinning of the blood. A long abstinence from sex or trauma to the penis or scrotum can also cause this problem. The treatment will depend upon the cause and this will usually be determined by urinalysis and culture and possibly x-rays. If there is an infection, antibiotics are used. The exact cause must be determined before the proper treatment can begin. Pain involved usually warrants a trip to the Dr. He/She will most likely rule out anything kidney or urinary tract first, then will most likely give you a good physical exam. Some men will have blood in their semen for no apparant reason and it will not cause pain and go away on it's own, however, with the pain, I would seek medical attention.
Hope this helps!
If my answer has provided you with some good insight today, please click "Accept" and I will received proper credit for my time and effort, otherwise, JustAnswer.com will hold your deposit. Before leaving feedback, please let me know if you need clarification or more info.
The info given is intended for educational purposes only. I give no medical advice and do not accept responsibility for the misuse of the information provided. If more info is needed please ask.