Most Helpful Guy
She obviously takes her studies seriously. Unless you know exactly her study habits or how long she studies I wouldn't advise telling her to take a break.
... It seems to me you need to give this some time. She's obviously stressed about her exams. Let her be stressed and study. Don't text her constantly and bothering why she won't text back as often. For real, be patient.
My advise for you is tell her "Do your best and you'll do fine on the tests!". Encourage her. Mentally support her. Take her out to eat after she's done with testing to celebrate or something. Support her.