Oh I totally sympathise.

It can be a number of things - do you think he may be unwell? Sometimes when little ones have earaches/headache or are teething, they will do things like that. It's possibly something worth investigating just to rule it out.

If it's not related to illness, then is it possible that it's related to frustration? Is he trying to learn new things ATM (I'm sure he is of course!). Does he have the kind of personality where he likes to do things by himself and gets frustrated when he can't achieve them? I know that this is the case for Jacob. He too will hit his head on things (he still does it at 23 months of age). He gets very frustrated when he can't do things the first time he tries them. We found that he did it even more when he was trying overcome the language barrier - he would get so upset and frustrated (and angry) that we weren't understanding what he was trying to tell us - and it was really awful to watch him get so upset.

The other reason he will do it is if we have said no to him for something that he wants - this is more often the reason behind it if he does it now.

HTH????