Ok, so I had sex 4 days ago for the first time in about 7 months and yes it was protected. The next day when I got out of the shower I noticed a red bump on my penis head. It looks like a pimple and there is only one. The bump is almost like a blemish you would get on your face, but its on my penis head... It has been there for 3 days now, what is it and or what should I do?

I would make a doctor's appointment and ask an educated health care professional to look at it.