Hi,
Most likely it is normal sinus discharge commonly we call as runny nose.
However, if it is clear watery discharge, it can be CSF leak. CSF is a fluid present in the brain area and nose has direct connection to your brain.
In my opinion, please rule out serious concerns like CSF leak. If it is not that, you can take some anti histaminics and steam inhalation.
Next Steps
Do not delay to rule out the serious problem. See a Neurologist ASAP.