1. You should try and collect this fluid in a sterile container and get it examined to rule out CSF (Cerebro Spinal Fluid). Get a Beta-2 Transferrin
test on the fluid, if available.
2. Your symptoms are similar to the 'teapot' sign or 'reservoir sign', where this fluid drips out on bending forwards or looking down.
3. A simple test is the 'Handerchief Test': Normal nasal secretions contain mucus which will stain and stiffen a soft handkerchief on drying, but CSF will not.
4. Do you have any history of recent head injury? Any ear complaints? If the above mentioned tests are negative, then you have allergic rhinitis
5. This is by no means an exhaustive investigation. Further testing depends upon the results (of these above mentioned tests) that you may post here.