Barbara, welcome!
You should ask your daughter's prescribing physician about stopping the Dex immediately. Stimulants like Dex are quick in and out medications and can be stopped suddenly, unlike other classes of medications, but I would strongly encourage you to discuss this with the doctor before doing anything on your own.
In terms of the insurance, the doctor can appeal the insurance company's decision not to cover Adderall. I'd recommend calling your insurance company to find out exactly how an appeal is made and then provide that information to your daughter's doctor. Your daughter's extreme reaction to Dex may actually help in the appeal.
Good luck.
