All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If you mean that moving your daughter from the Islamic school to a non-Islamic school may be the reason why she is afflicted with this disease, then this might not be the case. However, if you fear that your children will be affected with any wrong beliefs, or that they may miss the opportunity of being nurtured according to Islam and its creed and morals due to them studying in a non-Islamic school, then it is an obligation to move them to an Islamic school so that they will be nurtured in an environment that will help them be raised according to righteousness.
As regards the issue of your daughter having epileptic seizures, then this should first be treated with Ruqyah and then by consulting a specialist doctor. For more benefit, please refer to Fatwa 82355 and Fatwa 88705.
Allaah Knows best.