My 7 year old son Hits, bites, scratches and headbutts me and his step dad...

My son is 7, (8 in Dec) and for the last few years, when he is told off for something he has done wrong or is naughty, he usually either gets sent to his room or put in the naughty corner, but he doesn't go to either place without a huge fight.
We tell him to go to his room, his usual answer is "NO", so we tell him again, still NO, then we count to 5, still NO, so one of us will pick him up - if he refuses to walk to his room or naughty corner, we put him there, he will run away, and he goes MAD, he kicks, punches, bites, scratches us tells us he "hates us" etc... when we try to put him back.

But the problem is, he WONT stay in his room, or the naughty corner, so it takes us so long of him coming in and out, laughing at us, when we come to put him back.
Everytime we try, he runs away and slams the doors so hard the house shakes, and laughs at us.

If we tell him to go do something, like get dressed for school as an example, if he doesn't want to, he goes into another rage like this, hitting out, throwing toys at us or at the doors, screaming at us or me, or his 2 yr old brother too.

Today as another example, he was rude all morning, so i said he couldn't play his computer games, of course this made him angry and he was so rude all day, saying "i dont care" about anything i said to him, i tried to distract him, i tried EVERTHING but nothing worked, he got sent to his room for back chatting to me, and he scratched all down my arm's whislt and dug his nails in my hands as i was holding his legs to stop him kicking me, as he just wouldn't stay in his room.
Then my parents came to visit, he was well behaved when they got here, but when his grandad was helping him with his homework, he got stroppy again, he "couldn't be bothered to do it" "I dont care" he said.

Then he asked to play his computer games AGAIN so i told him No he couldn't as he was rude to me earlier. he went into ANOTHER rage infront of my parents, usually he wont do this infront of others, usually it's only me, his brother and his step dad.
My mum said maybe i should ask the doctor about behavior lessons/courses?
As they were actually shocked at his behavior, he was so rude to them, he kept slamming doors, hurting me infront of them, and would tell them to "be quiet" when they told him to calm down etc.
It was very embarrassing, as he is never like that infront of anyone else.

When he is told to do something, he just DOESN'T listen, it is like talking to a brick wall at times, he just doesnt acknowledege that i am asking him to do something, and when i have to keep repeating myself he will look at me then start going mad.
It gets extremly frustrating at times like i just cant get through to him no matter if i shout at him , or if i say it nicely, or if i explain it all word for word to him.
It doesn't get through so i give up and am left totally confused.

Sometimes he is utterly charming and lovely, but most days are like the day today that i described.
I dread my days sometimes because of it happening again.

Shopping and going out is another nightmare, sometimes he CAN be good, but mostly he wont behave or listen and gets very distacted by things whilst out, or he will talk a hundred miles an hour and really go into detail about everything he see's etc, he's very bright but sometimes it gets a bit much.
he wont really understand that i need to look for something in a shop etc, and he just goes on and on about wanting something that i just give in to him, for the peace and quiet.

Also sweets etc seem to make him worse, do you think he suffers from any type of ADHD or ADD etc, i have read about those, but i am not sure.
Any help would be very greatful many thanks.
sorry it is so long too.

I used to give him smack bottoms for doing things like that, but i dont bother now as he says to me "if you can hit me, then i can hit you" so i dont bother, it doesnt work for me anyway.

When he was 2, i split up from his biological father due to domestic violence, and he doesnt see his biological father.
I got together with his step dad when he was 3, and he has been like a dad to him ever since, so it's not like he hasnt had a father figure. He hasn't had any sad things to deal with as he was only 2 when i split up with his real dad, nothing else has happened or that can explain his behavior.

Unless i am doing everything WRONG????
I get so upset by it at times i just feel helpless about dealing with him, it really gets me down, and he is getting stronger and he really hurts me.

Could he have got his anger from his abusive biological father?


He is PERFECT at school, never been told off, every report is amazing, he is popular, helpful, his work is excellent..etc, so no problems there.

Please help me with some suggestions.