See pediatrician. Headaches in children can have a lot of different causes. Make sure your child has a regular sleep schedule and a good diet with no caffeine regular meals, and plenty of water/fluid intake. Headaches can be caused by allergies, migraines (esp. If other people in the family get them), or many other things. Concerning headaches usually come with vomiting, or occur in the middle of the night.
Not ok. Headache in this age group can be caused by a variety of conditions. It could be his sinuses, allergies, poor vision, stress or even migraines. He needs to be evaluated by his doctor.