Please help- is 99.9 considered fever on 1 month old baby?

Marsela

My 1 month old daughter been running a 99.9 fever since this morning! I’m so worried it may go up... i took it rectal and it’s 99.9 ... and on her ear was 98.7... should i worry? And what should i do so it doesn’t go up more?

First time mom and freaking out...