Hi, I'd like to help you with your question.
I certainly understand you being upset about this situation. It sounds like from what you told me that your daughter has been targeted by this teacher, who for some reason has an issue with your daughter's learning ability. There also seems to be a lot of miscommunication going on in the school about your daughter's abilities.
First, do you agree with your daughter's diagnosis of ADHD? Children can often be inattentive. That alone is never a sign of ADHD. There are numerous other symptoms that the child needs to have before ADHD is considered. The problem here is that the ADHD diagnosis has been overused in recent years and therefore Ritalin has been used in cases where it is not needed. If you agree that your daughter may have ADHD and you feel she is improving on the medication, then the diagnosis is most likely the correct one. If not, you may want to seek a second opinion.
Two, from the list of your daughter's skills and abilities, it seems to me that given her agel, she could be a gifted child. Playing a violin is not easy and it often takes someone who has mastered complex thinking processes. Also, if your daughter loves to read and is communicating with you and others in appropriate ways, there is no reason to believe there is anything wrong with her. What the teacher might be seeing is a child who is very high on the intelligence scale and she may not recognize what she is seeing. You may want to consider having your daughter's IQ tested. The current and most up to date test is called the WISC-III. You can talk with any psychologist for more information on how to get the test done. But if you do, you may have proof that your daughter is at least of normal intelligence, if not higher. It would also help her self esteem to know this information.
Three, it is illegal for the school to withhold your daughter's medication. They are not allowed to make decisions only a physician is qualified to make. You can talk with your attorney if you feel you want to pursue this situation legally.
Four, you may want to consider having your daughter seen by a therapist. She has been singled out by her teacher and other adults in this school and basically bullied. They have called her intelligence into question (something any adult should never do to a child, regardless of that child's abilities) and she has been led to believe she is different than other children. This is very damaging to her self esteem and possibly might affect her future academic performance. Ask her doctor for a referral to a qualified therapist who can help her.
Five, you may want to consider changing schools. It sounds like there are numerous problems at this school and the fact that a teacher and school nurse act like this without any recourse on your part is unprofessional and downright dangerous. I know you mentioned changing teachers, which may help. However, this may not change the situation enough to help your daughter.
If you do decide to have the meeting at the school, excluding the teacher is a good idea. Just be sure you do not feel she would take it out on your daughter. She sounds like she has issues and retaliation does not seem out of the possibilities for her.
Please let me know if I can help you with any other questions you may have.
I hope this has helped you,