Sounds like depression. Do be sure you are ready to go to work--have clothes laid out, some way of being sure you are awake in time to get ready.

Remember, everyone won't expect you to know much when you start work. They will train you. You want to do well so you will do the best you can. It will be OK. Tell yourself, I'm OK, I'll try hard, I'll do fine. Expect that, and it will come true!