5 yr old male. 100.1 fever. headache. no other symptons. what could be the cause? when should i take to a doctor? quick care

Many possibilities: Fever @ a 100.1 level is common in infants & children with a wide variety of minor and some significant illnesses.If kid is playing some & taking fluids well enough to pee every 6hrs, u may be able to ride this out at home. If excesively quiet, taking fluids poorly etc. Call in & or see the dr.

Hard to say: If your child has a low grade fever (less than 102) and is acting fine, you may be able to watch him for a day or two to see if it gets better by itself. Most viruses will get worse for a few days, peak for a day or 2, and get better for a few days, clearing up by 7-10 days. If he is acting sicker, fever is rising over 102, or there are new symptoms, see your doctor.