Q&A: Pimple On Penis, Could It Be Herpes?

I had unprotected sex about a month ago. Then this week, I noticed what looked like a pimple on the shaft of my penis. It popped on its own and had pimple ooze come out of it, like a regular pimple, and now it is almost gone. This made me scared that maybe it was herpes instead of a pimple. Could this be possible?