The doctor will check for fluid or infection in your child’s ears with an instrument called an otoscope. He or she would possibly observe your baby’s response to various sounds, together with your voice. If your child is age 6 months or older, ibuprofen (Advil, Children’s Motrin, others) is OK, too. Don’t use aspirin to deal with a fever in anyone age 18 years or younger. Turn on the digital thermometer and lubricate the tip of the thermometer with petroleum jelly.