3 almost 4 year old behavior changes

Hello all! Has anyone gone through behavior changes, sleep changes, or potty changes with your almost 4 year olds? Backstory, I am 33 weeks pregnant with my 2nd child. And probably for the last month, my almost 4 year son has started peeing in his underwear again during the day. He isn’t sleeping through the night anymore like he used to. And his behavior has been so bad. The hitting, kicking, slamming doors, yelling and screaming. It’s worse than just a “temper tantrum”. I have heard of things like this happening when big changes are being made in the home, so my initial thought was because of us bringing in another baby soon. I just want my sweet little boy back and am open to suggestions or if this is normal and he will go back to his normal self after the baby is born?!