Although I haven't had one for a few months, (although every time this thought comes through my mind, I usually end up getting one the next day, so I guess this post wasn't a great idea) I suffer from quite frequent nosebleeds, that can be quite vicious in sense that they are hard to stop. Once I get one it pretty much means I have to put up with them indefinitely for the near/far future until my nose decides it's "fixed" (slight sneezes or getting hot can set them off again if not). I dunno if its due to high blood pressure (which I don't think I have), or some other problem, but I've had them since I was very young but never bothered to go to the doctors about it. When I was about 5 I got my nose cauterized but I don't think it actually helped.
But anyway, more to the point; I've often had them from high up the nose, to the point where I get (gross detail following) a humongous clot falling down my throat into my mouth. And I don't mean some small little thing, this is a full on obscenely massive clot, it really is pretty grim.
I often think nothing of it as I've just gotten used to them over the years, and my sister seems to suffer from chronic nosebleeds also, but yeah, when I've researched it on the internet I've come across varying information, from it being highly "dangerous" to just normal, although most websites seem to be informing parents about young children with nosebleeds. If it concerns you, you should probably go to a GP or someone and get it checked out, or if you're lazy like me just ignore it (it might have just been a one off).