I'm 14 years of age, and I've been masturbating for nearly 3 years now. I've had absolutely no problems up until a few days ago. I've only masturbated today, and 2 days ago, but when I do, there is a burning near the head of my penis, which causes me discomfort. Any suggestions as to what might be causing this? My semen appears normal and when I urinate later everything is fine. The pain only occurs during ejaculation. Help?