Hi doctor, I m a 21 years old guy, I have an issue with my penis , I am not circumcised. But I haven t taken part in sexual intercourse with anyone else as yet. I have masturbated quite frequently before and found that after I ejaculate, there are fine pink, itchy pimples on the tip of my penis, underneath my foreskin , it feels sore at times... Is it and STI/STD? How can I treat it, or prevent it from happening again?