new job and terrified !

[Dinkiedoo]

Ive worked as a nurse for donkeys years and have now started working for a private company .Its a lot of studying and they are fast tracking me so I can work on my own in a couple of weeks and Im terrified.
I suffer with anxiety when someone watches me/ assesses me.
I have a big exam coming up and I have to be assessed as competent the week after and I am dreading it so much.
I know I am blowing out of all proportion but I just cant stop it .
I cant stop thinking about it and its disturbing my sleep.
I am working with my boss next week and I think I may mess things up because of my anxiety