thanks for query.
I think there might be a nasal contusion
and as you are a known case of VonWillebrand disease, bleeding might be due to local cause like mucosal tear or fracture
Anterior cranial fossa injury is another cause for nasal bleed, but as you have no other feature of it, it is less likely.
Better to have consultation with Neuro And ENT specialist
Mean while take anti inflammatory like Chymoral plus and normal saline nasal spray
like nazone spray.
Many thanks, take care.