This sounds like me as a child!!! It sounds like she has food allergies. Many doctors will tell you to make a chart of what she ate then her behavior, this is effective for spotting some food allergies but not all. Sometimes it takes many hours for a behavioral allergic reaction to show up and it can be difficult to correlate it to a specific food.
If you are in a large city, you may wish to have her tested. www.celiac.com has a listing of doctors. Celiac disease and food allergies are very closely related disorders.
If you suspect this is true, I would eliminate all food colorings in her diet immediately, then take her off of gluten (no wheat), peanuts, milk and high fructose corn syrup one at a time and slowly so her body adjusts. It may seem like there is nothing left for her to eat but there is plenty of vegetables, fruit, meat and rice. I am on this diet and if my mother had put me on this when I was 8 years old, she would not have had the temper tantrums, broken furniture/glassware, and overall heartache I gave her for 30 years. I would have done much better in school. Thank goodness I've reformed before she died. If you are near Tucson, AZ I have the name of a good doctor. I also go to a homeopath now and it has helped quite a bit too.