Small red bumps on head of penis.

I am a 20 year old male and last night noticed a few small red bumps on the head of my penis. I just noticed them after a day at the beach, where i walked around for hours in a wet bathing suit. These bumps are very small, they look almost as if someone dotted them on with the tip of a red pen. There aren't many only about 3, and they dont seem to be anywhere else besides there. I have had protected sex as well as oral sex with my girlfriend of 7 months. We have both been faithful to each other. You think this is an STD becuase we had protected sex and oral sex over 4 months ago and i had no symptoms until after the day at the beach. These bumps dont hurt or itch, and they dont ooze out anything. And they have seemed to get a little better then yesterday. I'm very nervous what they are, and opinions would be greatly appreciated.