Our 5 week old has been teetering between 99.2-99.7 all day (according to a rectal thermometer). My husband just took his temp, and he's 100.2. I'm freaking out!!

I'm putting a call into the doc, but I'm just curious what I should expect if LO's temp goes over 100.3. I'm trying to stay off Google, because I hopped on earlier to peek and it scared me.

ETA: my husband took his own temp. Baby girl's temp is still in the 99° range.