depression in young children

We have been having alot of probs with Chris' behavior lately. Very defiant, constantly either mad and screaming and yelling, or he's whining about everything. He's developed a mean streak, and has gotten so bad, the other kids in the neighborhood don't want to play with him anymore. If he goes outside, within 15 minutes the other kids will all go in cuz they don't want to deal with his rotten attitude. He's constantly getting in trouble at school - in the principals office at least twice a week. The assessment testing they do to see where a child is academically? They don't have any scores on those for Chris. He refuses to take the test. They've tried several times so far, and he just flat out won't do it. If you try to talk to him or discipline him, he either starts screaming and yelling, kicking and hitting and spitting, throwing things - full on tantrums ; or he just turns off. He'll drop to the floor, close his eyes, and reacts to nothing. One day, I pulled dowm his pants and smacked his bare bottom while he was 'playing dead' like that - no reaction. That always gets an indignant yelp at least. He's gotten very clingy with Eric. If Daddy isn't home - pretty much all Chris thinks about is when is Daddy going to be home. When he is home, the man can't take two steps with out tripping over Chris. Chris has also developed a dozen different little fears that he never had before.

Eric showed me an article he found about depression in young kids, and Chris' behavior sounds just like most of the symptoms named. Depression does run in my family. Does anybody have any experience with this, or know anything about depression in young children? I'm having probs with my medical ( yet again) but as soon as I get it straightened out, I plan to put him in counsling alone and all of us together in family counsling. I'm just hoping maybe someone can offer some advice or insight to maybe help until then?