Is this normal?

So my 15 month old daughter had a fever of 101.1 last night, woke up this morning and was 100.4 then 99.5. She napped and I checked it and it was 98.8, that was two hours ago. I just checked it again and it’s 102.1. I haven’t given her any medicine today at all. I just don’t understand how it’s going from 98.8 to 102.1. I’ve checked her temp rectally, on her forehead and ear and they’re all dramatically different. So I’ve been going with the rectal temperature.

I should also add she’s eating and drinking and acting normal.