My 4 year old has been irritable and complaining that his head hurts above his left ear, waking him at night.

Headache: Could be an ear infection, it could be a bug bite to his scalp. Schedule a doctors appointment if his symptoms continue.

Ears and teeth: Hi Lois507, A few causes of this pain are: Extension of ear infection to areas surrounding the ear. Referred pain from upper teeth can localize to the same area. A minor hit on the head can be missed with active 4 year olds but can cause unexplained pain later, a bruise in the area may be a sign of trauma. I would recommend a visit to his pediatrician, to rule out any of these problems. Thank you