My 4 yr old son has headache

He has had a headache for almost 24 hrs. Lastnight it was really bad. He was crying all night and barely slept. Today he said it hurt only when he shook it. And tonight he's saying it hurts again. He has a temp of 100.8. His dad and grandma have migraines. Is this a migraine or is this a virus? He hasn't thrown up. I gave him tylenol tonight hoping it will help.