I have an ear discharge, clear watery not very heavy no pain or head injury for about 12 hours .what can it be caused by please?

UNLIKELY NEUROLOGICA: If neurological would expect usually blood and hx of trauma. Clear fluid would be unusual consider ENT or pcp consult to help discover cause.

CSF leak: Clear drainage from your ear after a head injury is suggestive of a cerebrospinal fluid leak. If you have not already, you should see a neurosurgeon for further evaluation. Good luck.