Common cold, sinusitis, ear infection, sensory nerve compression, peripheral neuropathy as in diabetes, inflamed wisdom tooth
, impacted wisdom tooth
, dental caries, etc can all cause facial numbness and pain. Hemi facial numbness is also seen in Bell’s palsy, trigeminal neuralgia where a spasm may cause numbness, or due to acoustic neuroma which is a benign tumor of the eighth cranial nerve.
Maybe the accidental injury aggravated any of the above reasons.