Red spots on penis head

Over the last 60 days 3 red spots have developed on the head of my penis. I have had unprotected sex before. I do not believe this to be an STD based on how fast it came on, and research on my own. I am in a monogamous relationship and have been for over 2 years. It is always possible that it is an STD though.

The spots are 3-5mm in size. 2 are directly on the head of the penis. They are oblong and raised. They are shiny and have had skin peel before. The spots are raised. The 3rd red spot is on the base of the head. It is not like the other 2, as it is longer and less "round/oblong" in shape. The 3rd spot is right on the edge, and it has never peeled.

The spots are very annoying. They cause absolutely no pain, no discomfort, and no problems other than being in sight. I have not went to the doctor for this yet. I intend to do so if I am left without a definitive answer, but would like to avoid that if this is something common that simply goes away.

The location of the spots leads me to believe it has to do with masturbation. It almost seems like rough spots on my hand could have caused this. The spots are consistent though and do not fade or go away.

Thanks for reading, looking forward to advise.