Re: suddenly doesn't want to go to class
She does not have to go to movement and music class, so I wouldn't make her if she's adamant about not going. But, you could try giving her a choice of days. For example, you can present her with a choice of going this day OR that day. Having a choice in the matter might empower her a bit and make her feel more like going.
School is another matter; has she refused to go to school?