CRANKY BABY, DAY AN NIGHT

I have 3 boys, I have never had my baby just scream all night long, all day long. He is teething he is 4mths 3weeks. my cousins baby is one day older than him and she is doing the same thing.They have not seen each other in a bit so its nothing contagious I dont think🤔!but she is being the very same thing. they seem like they are running a fever or something serious, an it may be: hope not. However he don't have a fever, he just seems miserable. Prayers and advice please....