100F fever help 😔

A
My baby boy has some kind of cold. He got his 6 months shots this past Friday and I was thinking it's the reaction of. But he's had fever on and off all day since last night. I've been giving him Motrin and that's what's been getting his temp down but I'm not sure if I should take him to the ER? He's got a runny nose so much he can't eat well or take his pacifier. He can't sleep longer than an 1hr. I'm so worried 😔 help me someone out there