S.C.
I have a 4th grade daughter as well. Her behavior started to change around the middle of the summer. We are very close and I firmly believe if something was going on in her life she would tell me. She has always been a good student and behaved well. Her teacher called me 2 days ago and said she is not focusing in class and is very chatty. I was shocked. He was almost implying ADHD. We decided to try moving her seat. I will do anything to avoid putting her on medicaiton. I get hyper-sensitive about her emotional behavior because I have bipolar disorder. My first reaction was to get her a mental health evaluation, but then I was talking to my therapist about her and came to a logical explaination. I got my period when I was nine and she is probably going to get hers soon too. My therapist said that girls can start having premenstural syndrome symptoms up to 2 years before they get it. Their hormones start raging and it causes a lot of extra energy and confusion which can lead to acting out. Anyway, this is just one possiblity that you could explore. When I sat my daughter down and explained some of this to her, she started to cry and said she feels like she can't control herself and is easily distracted, but she wants to do good in school. I'm just staying on top of her and watching her very closely for now, hopefully she'll make some changes.
Good luck to you and I hope you ge to the root of her problem.