Big Test anxiety, how can I keep calm while studying?

I have a major test anxiety. My midterm is a week away and try to study on the weekend. But I keep panicking and try to rush the information in my head. I keep panicking especially right now. I already fail the first test due to my anxiety and now I can't fail anymore. Just great. How can I stay calm and get information efficiency? Especially for calculus 2 and calculus-based physics?