Rectum temperature...

My son has rsv he starts day 5 today. His under arm temp is 99.6 I’m so against sticking anything in his rectum. I’m just nervous and don’t want to hurt him. When my daughter was in NICU 5 years ago, our NICU nurse reassured us so many times going by the under arm temp was okay and very accurate. But for some reason I feel like it’s not with my son.. maybe I’m just feeling guilty. Any other moms not want to do rectum temperatures. 😭