When I was a kid I used to get nosebleeds all the time. I never found out why, exactly. At first I would feel a warm, thin drip. Not the same viscosity as mucus. Then there would a taste at the back of my mouth, like sucking on a penny.
For some reason, I would be sent to the principal's office to wait out the bleeding. There would often be a little argument among the administartion as to whether I ought to lean back or sit normally.
Eventually I got so used to getting them, I just warned new teachers on my first day: "You should know that I get a lot of nosebleeds", with a cheerful delivery that I thought played down the drama, but ultimately branded me dorky.
I don't know when they stopped, but they did. I can get hit in the nose with a basketball (true story) and nothing happens. I must have toughened up. Without knowing it.