if she doesn't have a psychiatrist, go see her family doctor. he/she may be able to give her medicine to take just before this anxiety starts. maybe an antianxiety or even phenergan for nausea but leave that up to the doc. i get physically sick from anxiety sometimes but i take xanax and pray it away. i don't take the medicine very often but it's there when i need it. see what her doctor says the sooner the better. maybe consider therapy to deal with the underlying issue, keep an open mind and it's nice to have a parent who cares so much for their child, hang in there.
i forgot to add, if your child has general anxiety issues, i read in a magazine that sage leaf extract can help, but read up on it. good luck