W is five and a half months old, and has had a mild fever since yesterday afternoon. The highest I've seen it is 101.7. I tried to give him Tylenol yesterday but immediately after I gave it to him he threw up everywhere, so I don't think that helped much. This morning he's still warm, I gave him Advil but not sure how much actually got swallowed. He's still nursing, doesn't seem lethargic, and is having wet diapers, he's just grumpier than usual and going for naps sooner.

How long do you let a young infant have a mild fever before you see a doctor? If it went higher or seemed to be affecting him in some other way I'd go but with just the fever I'm not sure.