My 6 year old was diagnosed with a mild concussion a month ago he now complains that parts of his head hurt and is now waking with night terrors which?

Head Injury: There is no such thing as a "mild concuson" the old grading scale has lost it's usefulness. We know a conclusion is a conclusion, and everyone recovers differently from each episode. Rest, avoidance of screens (tv, cel phone, video games, etc) and rest are the best ways to get over a conclusion. However, in you son's case, in think it it time to have a reevaluation of his condition.

Mild ?: Kids do occasionally have headaches associated with even modest head trauma up to a month after the event. Whether this represents that event or something else would require an evaluation. Night terrors are more likely a reflection of sleep habits that have suffered leading to a deficit of effective sleep. Worth a re-check.