Just brought home newborn and my toddler has a fever

I am feeling completely overwhelmed and anxious about this, so please keep replies reassuring. I have a 4 day old and my 1 year old woke up today with a fever of 101.5. He has literally never had a fever before, so I have no idea what to expect. He has no other symptoms and is acting totally normal. Has anyone been in this situation and have any advice or words that will ease my anxiety? I have already called the ped and have them in separate spaces, but not sure what else to do. This is my miracle baby and not how I planned our first few days home to go. I also have mastitis, so trying to deal with that as well. With postpartum hormones I just can’t stop crying and worrying right now.