Needing a little help!

Our son is 9 1/2 weeks old. We have been blessed with an incredibly easy baby BUT this past week he's been extra fussy and even hysterical. There's also some new slobbering. He had his 2 month check up on Monday. He had painful legs from his 5 shots, slobbering started, vomiting more than the usual spit up and he had a slight fever the day of. I think he's teething but isn't it a bit soon???