I am running out of options here... HELP!!

[aeasterly]

I have a 5 year old daughter who has become progressively violent over the past year or so.  It all started off with just screaming at her siblings and us, calling names, and the occasional "I hate you!!".  She has always had an attitude problem even with adults.  We thought that maybe socialization might help so we enrolled her in pre-school this past year.  Although she did rather well in the classroom, she was a terror on the bus.  She would hit and kick people and was yelling and being VERY rude to even the bus monitor...  There was one day that she refused to get off of the bus and go in to the school, but her fit was so horrible (kicking, hitting, and screaming at everyone) that they just decided that they would let her sit there until she calmed down.  About 45 minutes later, she finally got off the bus.  All of this was because she had forgotten her back-pack and it wasn't good enough that I was going to just bring it to her at school on my way to work.
Then, I noticed she was starting to be mean to the animals in the house.  Kicking and hitting them for no reason, and then the worst one was when she had a hold of our cat by the neck and threw him down the stairs.
Now she has began hitting her siblings (one 6 and one 2).  She no longer says I hate you, but has replaced that with "I don't care about you" which is nearly just as bad but a little more polite...  Today, she was playing in the back yard on their air-filled ball pit/trampoline with her brother and sister when my husband witnessed her laying on her back kicking the others.  She kicked our two year old in the stomach and in the mouth, kicked our six year old in the legs and head so hard that she knocked her out of the ball pit.  She then got out, went over to her sister and punched her so hard in the nose that it broke her sister's glasses...  all this in the time that it took for my husband to run across the yard and grab her off (about 15 seconds)... all the while she was smiling and then told my husband it was an accident.
I have tried everything with her.  We tried positive reinforcement, (which helped for about 2 days then she was over it) time out, (we would sit her in a chair facing a corner in an isolated room for a period of time.  We also sat an egg timer where she could see it so that she would grasp the concept of how much time she had left)  I've even resorted to spanking her on the rear end but then it just makes her fit grow worse.  
I've gone to her doctor (which when we got there she was an angel) with my concerns and he suggested a book called 1-2-3 magic.  We read it and tried it out but it didn't take her long to realize that she got the first 2 free-bee's before she really had to stop so that was not very helpful.  I just don't know what else to do...  I'm at the end of my rope and her behavior is beyond the point where I think she's just acting out for whatever reason, now I am beginning to worry that this is the beginning of something bigger and I don't know how to stop it.  She is such a good kid when she wants to be, and I've done about everything I know to do...  HELP!!!

[LRM1021]

I agree with the post above. Its time to take her to a child psychiatrist for an evaluation -- to get a handle on what is going on with her so that you can help her. You have done all that you can without bringing in professional help-- and its important to do so very quickly as she sounds like she is able to hurt others and herself. And I also agree-- until she is evaluated she should not be left alone with other children or animals.

[cesmiles4u]

she sounds like a very smart little girl   Have u taken her to a child psychiatrist or psychologist?  That would be my next step.  In the short term I guess I would make sure that she is not alone with her siblings.  She wants to play in the pit, last time she hurt others, this time she sits out and watches her sibs.  But, I definitely think there might be an underlying disorder.  My son was diagnosed with bipolar at age 6.  He could be aggressive and would tantrum like that for no really good reason and need to be restrained.  Sometimes just because it was time to go home from Grandmas house.  Good luck