He hasn't had his 4 month vaccines yet. I have an appointment scheduled for that tomorrow, but he just woke up to feed and I took his temperature and I first got 99.9 then 100.4 just seconds after. I take it a few times under the arm, just to make sure. Is it OK to give him baby's Tylenol and a bath and see if that helps? Or should I just take him in? I honestly have no clue why he'd have a fever. The only things I could think of is that we went out last night and it was pretty cold, but he was well covered. Maybe that he got cold in the middle of the night or something. I wanted to give him medicine and if it helps, I'll just wait until tomorrow's appointment. If it doesn't go down or comes back the same, I'll try to see if he could be seen today.

EDIT:: he's acting/playing normally. He's also been showing signs of teething for a few weeks now.