Looks like everyone's given you some great advice...actually the same as what I was thinking
. It could be a number of things that are causing the nose bleeds (hypertension is a big one, but it could be as simple as the air being really dry). My suggestion would be to fire up the humidifier (hope you've got one!). I used to get nosebleeds daily when I was a kid & after much research the doctors found that the air was too dry for my nasal passages. Once we started using the humidifier, I never got one again. If you don't have a humidifier, you could boil some water on the stove & try breathing in the steam. That will help temperarily anyway.
Another thought, are you on any kinds of medication? What about aspirin? Aspirin will thin your blood & has been known to cause nose bleeds if taken regularly. I would definitely eat more green leafy veggies & see if that helps too. But only do that if you are not on any medications for thinning your blood (like Coumadin or Warfarin). Those two shouldn't be mixed unless a doctor recommends them because the greens will prevent the med's from working correctly.
For right now, I'd get a cold pack from the freezer & hold that on your nose. It may feel weird & ackward, but it will help stop the bleeding. If this persists, definitely get checked out by a doctor!
Hope this helps you!