My four year old has woken up the past two nights complaining of a headache in the back of his head. He has had a fever (peak of 101) which has been manageable with Advil, but it keeps coming back. He has an appetite, is drinking water, and plays quietly. My other son (20 months old) had a virus last week that caused a fever (also 101), but lasted only 48 hours. My older son is able to show me where his headaches are (on the back of his head), and this has me concerned it is something more serious. Please advise. Thank you.