My puppy is acting a fool

Hi all! I’m a first time puppy mom! We have a 4 and a half month old. And he has been doing SO good with behavior lately (nipping, barking, potty training etc). But all of a sudden this critter decided he wants to act A FOOL out of nowhere. He has been barking constantly, nipping, chasing the cat and peeing in the house all day. Is this some sort of terrible two phase? Is this normal? I feel like we have regressed so much in 24 hours. We have changed nothing about our schedule and I’m so confused on where this is coming from. Plz help 😂😭