I didn't take time to read other responses, so sorry if it's no longer bleeding or if you've already had the vet out.
But, please, call your vet and get them out there. My horse died unexpectedly and tragically of a suspected guttural pouch infection, as she had never showed any symptoms, which is common. Even though we had her on an IV fluid from the time she was brought in, she passed away hours later after having a steady nose bleed that we couldn't stop. The whole time, it was only a steady trickle, although at times, it did get faster.
I'd also get her scoped, since that is really the one way you can know. Even if it's stopped, that's not to say that the next time, it won't be the final nose bleed that does have more serious consequences.
Forever loved, never forgotten; my beautiful Indie. <3 Hoofprints on my heart.