(Question) Why does a nosebleed happen?

I don't remember ever having a nosebleed.

But today I had a nosebleed.

I go swimming at 6 a.m. in the early morning.

I was about to enter the swimming pool after getting ready.

I had a continuous nosebleed from my nose.

Standing at the showerhead, I keep wiping my nose.

If you have a nosebleed next to you, you shouldn't tilt your head back.

You can't block it, and you just have to stay still.

They said they did it.

I stood there for over 10 minutes, and then my nosebleed stopped.

I went swimming.

Why do I get a nosebleed?

I slept for an hour two days ago, worked all day, and then went to bed early as if I were dead that day.

I have never done anything overly strenuous.

There is no pain anywhere.

I'm curious about the reason why I suddenly have a nosebleed.