Hi Keyslost. I know how stressful tests can be.

Try to eat a high protein low carb diet with meals or snacks every 3-4 hours till the testing is over. Exercise helps. Sleep as much as possible even if naps for an hour or two.

If mind races, I try this.

Breathing exercise with normal breath.
If you are feeling very anxious or angry or just want to calm down, you can try a breathing exercise that takes the attention away from the trigger of anxiety to a simple tool of counting breaths.

Find a comfortable position seated or laying down. Begin to relax your breathing. Silently count 1 on the inhale, and two on the exhale. Then silently count 3 on the inhale and 4 on the exhale. Continue up to 10 or until you lose the count then return to one. No judgement. I sometimes end up at 18 then smile and return to 1. The idea is to focus on the breath and the counting and not get sucked into the anxiety or anger trigger. Also works to quiet the mind.