Toddler

How did you stop your toddler from screaming and throwing things ??? Hes 2 and recently we had his sister ...but hes never been this bad maybe it has something to do with leaving his sister with my mom and my 5 year old sister I'm not sure ...the baby isnt fazed anymore by his screaming but its embarrassing though especially in public...and the throwing things I'm so scared he'll hit her with something.. please help.