My son (nearly 4) has some days where I can't seem to engage with him, he'll spit or makes loud noises in people's faces and laugh when he is asked to stop. He will constantly move or fidget, knock objects off the side or damage things, not sit down to eat. He hasn't made any friends for a while and the one friend he did make was very bossy and dictated the friendship. Other days I can play with him with only a few unwanted behaviours and he's like any other child. It puzzles me as I don't know how to get through to him on an "off" day.