Don't panic.
Concentrate on your preparation right now.There is no point in worrying about score.
I too had anxiety and panic attacks before my entrance.
Just remember everything you have read will be retained in your memory,right now you may feel that you forgot some topics but you will be able to recall in the exam.
Prepare a schedule 1day in advance before going to sleep.just concentrate on topics that you are weak and avoid silly mistakes.
Next Steps
practice Grounding technique for anxiety every day.
Health Tips
regular breaks during preparation for every 1hours helps your concentration