Baby temperature

Hi mummies my infant is 3 months old and his head feels warmer than usual. I measured his temperature at the armpit area and is below 37 degrees. His forehead temp is a little higher but below 37.5 degrees and this has been going on for about 4 days. I thought it could be the thermometer is spoil. But i tried 3 diff thermometers and the readings are all about the same. Is this normal? Anyone faced this before?