My almost 7 year old has had 2 BIG nosebleeds the past two days, when in her room. I don't think it's particularly dry in the aptmt, but I ordered a cool mist humidifier that's coming tomorrow. Anybody know if this can be something serious I should worry about? Because you know, we don't have enough to worry about...But I've never had one, and it comes out like a faucet. thanks in advance!!

To be safe I would call the pediatrician and schedule a video appointment. No one's advice on this compares to that of your doctor.
I would call the pediatrician too. My DS who is 6 has always been prone to nosebleeds especially in dry winter months, but it's never like a faucet and it's been this way since he was small. I would be concerned that this has come on suddenly. If the pedi says it's just dryness, Ayr gel saline in the nostrils can help.
thank you!