OP, I just wanted to thank you for posting this thread. I have wanted to for so long, because I am going through the same thing with my DS (10). It has gone on for way to long, and I need to stop it now. At his age though, it's a little embarrassing to talk about.
Like others, he is very well behaved at school. Two years ago he was not doing well in reading, and would not focus. I asked his teacher if she thought he may be ADD. (because of home behavior as well) The school system ran all kinds of tests, and after months of this, it came back normal. I also talked to his Dr. about it, again, normal.
He will be fine at school, then he will get into the car in the afternoons and snap. It's like flipping a switch. Not on most days, but sometimes.
He has gotten a little better, however his explosive anger is still in him daily. He will get so mad over the dumbest things. If I don't do something fast enough, or if I refuse to get something for him that he can do himself, DD can look at him wrong, and off he goes. He will slam doors, scream and carry on. It's ridiculous. He even tells me that he hates me. Sometimes when it gets really bad, the only way I can calm him down is to talk him into taking a shower. It gives him time to think and to calm down. Once he gets out, he is fine. Needless to say, he is a very clean child.
I have also noticed that it's hard to get his mind off of something once he is focused on it. It's like he is going to get it no matter what.
Recently he has made some improvements, and I brag about it when I see it. He is doing well in school, he is really proud of that. I have to study a lot with his sister and he has been jealous of that. So he has requested that I study with him more too, which is great, but this leads me to think this is an attention thing, or a control thing over me
Another big issue is that he has to be with me all the time. He wants to know where I am in the house, he will not go to bed unless I am lying down with him, and after I get up at night and go to my room, it's nothing for him to wake up later and come get me.
I am also giving him Melatonin at night to help him sleep, but it does not keep him asleep. This has been a big issue for me, because I am not sleeping well at all either. You see that it's almost 1am my time.
I'm sorry this was so long. I am going to go back and re read this thread. I have not had a chance to read it all, but there is some great advice here from what I have read, that I am going to try. Hopefully it will help me out too.