This is not an uncommon condition in people with anxiety disorders.
You have two main options.
1) Take something to calm you before going in like a xanax etc (not a
preferable option, obviously).
2) Relaxation exercises. Have you learn about Combined relaxation,
and the associated isometric relaxation techniques which are designed
to calm you down wherever you are, whatever you are doing? These
are good because they dont draw attention to you, but can be quite
effective. They arent going to drop your anxirty through the floor, but
they will help you to control it in situations which trouble you.
