Red spot on penis shaft

Hey guys,

Hi. I (30M) have noticed a red spot on my penis for three days ago. It doesnt itch or anything. I am sexually active, but use protection almost everytime. I will see a real doctor, but I cant get an appointment before next week. Until then, I hope someone will shed a light on what it might be. Have you experienced something similar, and if so, did you find out what it was and what helped?

It is not that red on the pic, but becomes more so when erect.