Isa,
We had the same situation with our son last year. He had upset stomachs to the point of throwing up on the way to school and constant headaches. After many Doctor appointments and evaluations and nothing concrete coming back, we learned that DS had internalized so much in school that it was actually turning into a toxic environment for him. The teacher he had was not a bad teacher, she actually seemed to do very well with most of her students. However, for DS, it was an impossible situation. She was actually emotionally abusive to him without even knowing it. (Believe me I am not as calm as this post sounds about the situation...)
My point is I would definately do my best to get your daughter out of that classroom if the ailments return. If the school will work with you that is great. If not, you don't lose anything by taking it as high as you have to even if it does mean calling the embassy
Good will with a school seems to last only until you ask for something they do not want to provide.
