Advice?

Anyone have advice on ways I can get my 20 month old to stop screaming and hitting? He will literally go around the house and scream this ear piercing high pitched scream. He has also started to hit a lot.. I tell him to stop numerous times but nothing is working. I just gave birth to his baby brother on the 25th and I’m really struggling with disciplining him. He will try to hit him as well as his father and I. I expected him to act out due to the change but I didn’t expect it to be this bad.