my son does the same thing, he turned 4 in April. I notice (of course) that it gets much worse with stress. If mom and dad are stressed, he's stress. If anything in his daily routine changes, it's worse. Like if I'm behind in work and need to focus on it, attention is less on him, and he reacts. Strongly. He's also started going this HUGE rebellious stage. telling me no, telling me what to do, telling me what he's going to do. He's testing his boundaries Big time and trying out being like his role models (mom and dad). I wish I had more control over him, but even if there is a long struggle, I do eventually come out on top.....I think...This is not the only phase he's gone through where he's been violent and acting out badly. I think they are phases, just testing. And even though it can get extreme, I think as long as I stand my ground and don't back down, keep everything as normal as I can while enforcing the rules, It will pass. even if it takes waaay much longer than I think it should or could. Believe me I feel for you.