Coagualted blood under nose - Help !

[Dejan Pavlovic]

Our Laureen has a few drops of coagulated blood under nose .
She doesn't sneeze or click . She acts completely normal.
Bedding is - toilet and white printer paper only .
There are a few wood pieces (not cedar or pine) that they gnaw in their
aquarium .
What could it be , and what shall we do ?
Help please !

Many thanks !

Dejan & Nives