Variety of things. Many things can cause this, is there a family history of headaches or migraines? When did this boy start his growth spurt, have puberty hit? Is there a pattern to the headaches, like always in the afternoon, weekdays, weekends, wake him up from sleep? Does he have allergies that cause congestion? Does he drink coffee or use energy drinks? There are too many questions for this forum, see your dr.
Migraine? I would have him seen by his doc to evaluate for the headaches..Especially if this is a new thing... It may be migraine, but should be properly diagnosed and managed good luck..