Baby’s temperature

I’m pretty sure my daughter is teething because she’s been feeling a little warmer than usual and a little fussy at random times and she’s at the age. How could you tell if your baby is running a fever without a thermometer? (If it’s possible). I have a ear thermometer but it always says different temperatures and isn’t accurate at all. I’m going to buy a rectal thermometer but wouldn’t want to use it unless it’s necessary. Any advice?