What Causes Vomiting And Sleep Talking In A Child?

My 10 yr old daughter wakes up about once a month vomiting everywhere! Its always in the middle of the night and she will have vomit in her bed, floor,etc.! Sometimes it will only happen once, but it usually happens a few times before morning with usually no other symptoms and she wakes up fine! She was a horrible bed wetter until a yr. or so ago, and then this began! Shes also a sleep-walker, and before she was sick tonight, i heard her talking in her sleep! Weve tried to pinpoint a certain food that could be causing this but what she ate tonight, i know shes not allergic to. One last thing, she complains often of headaches, normally in the afternoons, but i thought it was from the hr long bus ride home from school!