Hang in there! My daughter is going through the same thing. I have been extra tough with her as a result which I think was back firing. I am laying off her a little and giving her extra 1:1 time in the evening which is helping a lot. When I say laying off her I am just not "always on her" like I was which was not helping and making her act up more to get that negative attention. I am continuing to praise the other kids as well when they demonstrate pro-social behaviour and she is noticing this as well. I also give her a few special privileges like staying upstairs in the morning to watch TV if she chooses before the school run and although she has been choosing to go in the daycare I think she likes having the option. We should start a support group as this is not a unique issue!