what happened to my baby ahhh

My LO was so quiet such a good baby rarely ever cried. He would usually fall asleep on the boob when he was tired he'd take a couple sucks of milk just to fall asleep. Now he's 9 weeks old and for the past week one or two times a day it's like he gets overtired and screams and screams. He won't stop to take a breast and he doesn't like pacifiers. The only thing I can do is walk and rock and sing to get him to fall asleep. Sometimes takes a while. He got his shots Monday I thought it was that but don't think it's still from them 5 days later. Any tips at all? Please help!! He sleeps well at night btw.