After you jack off just kind of wipe the semen off. After a day or so you can notice a little Musk. If you touch it and smell your fingers you will know what I am talking about. You might find the smell a little off-putting but that's because you are a guy. Amongst the smell is many natural pheromones that trigger a response in women. It is basically a subconscious signal that you are fertile and ready to meet, it triggers subconscious actions much like how when dogs are in heat. Human biology has adapted in such a way that women are attracted to the scent. It is similar to why a guy likes to smell a woman's underwear because she has left her scent on them. The biggest key however is making sure you at least wipe off any semen after jerking it, and possibly even a little quick rinse DO NOT take a bath. Showers are okay just don't spend any time soaping up your mr. wizard. You want to keep the pheromones and scent on a fairly mild level however so if you start to notice a smell when you lower your pants to go to the bathroom or to jerk off some more then it's time to actually soap up that big boy and get it clean but in the meantime let your man smell ride
I have the same it is dirty pores from not cleany up
I masturbated and left my cum overnight and now its red and becabe bigger
It could be a fungus issue seeing your doctor would be the only way to get a proper diagnosis.
You could try an over the counter cream for fungal infections to see if it clears up.
Cleaning yourself properly is something you really need to start doing everyday and after you masturbate use a mild soap that won't irradiate your skin.
You or others may have already noticed that body odor is becoming an issue proper hygiene is very important and you need to start looking after yourself.
If the rash does not clear up after you use the cream and start cleaning yourself properly for a couple of weeks see your doctor it's an early sign that not cleaning yourself properly is causing you a problem.