First, try not to let your anxiety carry over to him. Don't assume that what goes on with you also goes on with him and don't allow your anxiety to increase his. That's really important as an anxious parent.
Does he have headaches often? Migraines? Less common in boys and for his age but cluster headaches can occur. Remember too, he's been ill. Probably related.
The best thing to do is to set up a doctors appointment with his regular pediatrician (not urgent care) to discuss what is going on. This will provide best answers and give YOU peace of mind. good luck