LO not eating??

My little guy has been good at eating. He’s a month old and we got to the point where he wasn’t sufficed until we would give him extra. He’s consistently ate 3oz for a couple weeks now. He’s a month old. Since Monday he hasn’t been finishing any of his bottles and when he’s eating he’s squirming the entire time like he’s uncomfortable or he just passes out. Most of his bottle has been ending up on his chin anyways. My baby has always been the kind to eat super fast so we have to pace feed. But lately it’s taken about an hour and a half just to get him to finish those 3oz. Anyone know what could be going on or have experience with this? We have a ped appointment tomorrow morning so we’re gonna talk to him about it.