He is just not responding to any of my tatcics. I have tried positive reinforcement for good behaviour, a star chart, taking away treasured items when he misbehaves, naughty step/chair - NOTHING WORKS! He is seriously aggressive towards me (I have just had an operation on my stomach and he keeps kicking me there) and recently has started spitting at me, in my face, and all over everything. He only seems to respond when threatened with a smacked bum, which is completely counter-productive and setting a bad example and I HATE doing it.
Please help. Any advice is greatly received.