My son was 2 two days after my new daughter was born. He was amazing for one month, but has suddenly gone really naughty. Until just a few days ago, he was a spirited, active livewire of a boy, but suddenly he's shouting no at everyone, being possessive of everything (he shouts 'mine!' about everything), chucking everything on the floor, pushing other kids around, looking for things to get attention basically. I'm trying my best to include him with jobs with his sister, but I'm finding it really difficult to be able to cope and know how to keep calm with him. Does anyone have any ideas please?