‘Headaches are common in childhood. Most of the time, they are nothing to worry about and are caused by common minor illnesses, a mild bump to the head, lack of sleep, not getting enough food or drink, or stress. Migraines can also be seen in childhood, but with awareness and avoidance of triggers, they don’t usually cause problems.’

https://www.health.harvard.edu/blog/8-things-to-watch-for-when-your-child-has-a-headache-2017051611761