Ear hurts when i open mouth after hitting head. what could be wrong?

Get a consult: How did you hit your head? If you hit it hard enough you may have dis-located your jaw or causes some joint damage and inflammation. You may only need simple treatment or some anti-inflammatory meds but better to know now. See a dentist or a TMJ specialist.

TMJ disorder: Post-trauma TMJ patients always report earache, neck pain, and headache as well as sleep disturbances. See OFP specialist for diagnosis and treatment.