Help 😩😩😩 parents of 2 or more!!!

I'm going crazy! My almost 4 year old is completely acting out! Since I've been pregnant he's been misbehaving & I no longer know what to do with him , we don't hit him because it solves nothing but anything we say or do he's crying and screaming just acting out, he's nasty to other family members not wanting to be bothered or gives hugs and kisses he's just completely not him self! , any one been here? Advice please!