My 3 month old baby has a temperature of 38.3 only from one side ears he was sleeping on and under his arm. is this normal?

Slightly elevated: This may be a sign of infection. Continue to monitor the temperature and if it is 38.5 or higher, baby Tylenol may be given. Continue to feed as usual, and watch for signs of a respiratory infection. Other causes include an ear infection. If there is an elevation in temperature for more than one day, signs of poor feeding or lethargy/irritability, please see your pediatrician on the same day.

Not from the ear: A core temperature of 38.3 from the ear is above 101F and should be evaluated by a doctor ASAP, especially in a baby at 3 mo of age, also make sure you are treating said fever with Tylenol at a dose of 10 mg/kg every 6 hrs