Oh Ellsbells it must be so hard for you

It probably is a good idea to get him tested for ADHD, just incase. Do you think it could be because he is jealous of your little girl or did it start before that? If it is then maybe you could try doing something with him that he likes (painting, craft) just you two and giving him lots of cuddles and telling him you love him? Then maybe he will forget to be cranky IYKWIM?

I'm sure it is just a phase and I know that that doesn't really help but i'm sure it will pass. Sorry, i'm not sure what else you could try , maybe talk to one of those people like Super Nanny (not her but someone like her!)?

Hugs for you and I hope it gets better soon.