What Causes Nose Bleeding Along With Severe Fatigue?

My daughter (age 11) just recently started having multiple nosebleeds daily over the past 3 weeks. She just recently had the flu and we do have a fireplace in the home but it has never bothered her in the past. We live on the west coast so its not particularly dry and cold. It s actually been quite a warm wet winter so far.. The main reason why I m worried is that she has gotten very pale over the last 2 to 3 weeks and she is very dark in her eye sockets. She has been extra tired and fatigued. I have been making sure she s getting enough sleep and water ect.. she had open heart surgery when she was born and still has a bicuspid valve. Her aorta was reconstructed as well as a large patch between her right and left ventricle. Between her history, her symptoms now and such, I am worried. What could the nosebleeds be coming from. They are a pouring kind that randomly start dripping whenever and where ever. At home, at school, in the shower.. basically multiple times and day