8 year old adopted daughter

Hi,
My 8 year old daughter suffers from big tantrums, and much anxiety. If she does not get what she wants much of the time she will become angry, and scream, and sometimes even hit. Afterwards she is sorry, and does not know why she does it. She has had a difficult time with sleep since she came home from the orphanage at 8 months. She does not like the dark, and has many fears at night. She also has fears in the day. she won't go to the bathroom at school and hold her bowels which then sometimes leak. She has become so picky about food she will eat almost nothing. she loves pasta and sugar even though we restrict both. she is often so angry, and becomes really mean. we are giving her some amino acids right now that help with sleep and perhaps a little with her anxiety. she is born in Guatemala, she is mayan indian, dark skin and hair, small strong and healthy body. she has suffered many upper respiratory problems and whenever she gets new teeth gets very sick with bronchitis, and thick yellow mucus. i try to keep her from eating dairy as well. please can you help with her anxiety and anger?