What's the deal with bloody noses?

My sister used to get them all the time when we were kids. But my first bloody nose came at age 10 when my dad (accidentally, of course) hit me in the face with a soccer ball. We were on vacation in NoCal and it was my first introduction to the sport. Needless to say I never became much of a soccer fan.

After that, the only naturally occurring nose bleed that I can remember having was around age 23. We were living in Ames and I got one in the middle of the office one day. I totally freaked out and all of my co-workers thought I was weird because I didn't know what to do.

And that was my only experience ... until last week. Last Monday, we were taking down the Christmas tree (I know. It should have come down before then.) and my nose started bleeding. Last night I was laying in bed about to fall asleep when it happened again.

So, what's the deal? What is going on that suddenly my nose is going crazy? And, more importantly, how can I make it stop happening?