What Is The Treatment For Pimples On The Penis?

So i havent had sex in almost 4 months. About 1 month ago i noticed 2 pimples on my penis shaft and then just this week i had a pimple on the tip of my penis near my urethra. They are not sore or irritated but im just worried. could this be an std? I thought herpes you usually show the first signs within 2-10 days. Its been 2-3 months since my last sexual encounter. Any thoughts?