How do I know when my toddler has intrusive thoughts or just being bad..

I’ve been suffering from ppd and I haven’t been all the way there. I have a toddler and an infant, My toddler has been “acting out” kind of being suddenly mean to the baby not hurting him. He’s been doing things like throwing and yelling. I’m thinking maybe he’s bored he’s starting school soon we had a hiccup with our insurance so we weren’t able to get his physical for school… anyways so how do I know if he’s acting on intrusive thoughts or becoming a meany… ?

Edit: my son is 4