Baby with a fever! Please help!

My baby, who will be 3 months old Friday, was at her grandmas house all day today while I was at work. When I went to pick her up, her grandma told me that she had been sleeping most of the day today. I found this odd since she’s been awake a lot more lately. Once I got home she felt really warm so when I took her temperature it was 100.6. I tried calling her doctor but nobody has called me back so I have resulted in posting on here to see if other moms had any advice on what I should do to break this fever! This is my first baby, and to be honest, I’m kinda freaking out! 😞