Unfortunately it is not uncommon for teachers to have students that suffer from test anxiety. That's why it is so important for teachers to have a strategy in place when students become overly nervous, sometimes even to the point of making themselves sick.
S.B.G. or Stop. Breathe. Go is a relaxation strategy that I use with my students. It is simple and can be carried out just about anywhere. Basically I teach my students that when they are feeling stressed or anxious the first thing they do is STOP. Then BREATHE, or take 2-3 deep breaths. Lastly, it's time to GO... or continue working.
These bookmarks are quick reminders of the 3 steps involved in S.B.G. I hope you find them helpful with your own students.