I think every nurse has had this experience. And every time you stretch yourself with a new skill, job or dept the anxiety can creep back into your life. I like you started in the ER about 3 yrs ago and for the first year I was often anxious before work. In fact I used almost all of my PLT time by offering to be the first to go in the first 6mo. But after I experienced the same critical care scenarios again and again I increased my confidence and the anxiety went away. I have since started traveling to stretch myself once more and I am all the better for it. This job isn't easy and it is full of the unknown. I think you should forge forward and master the skills you need. You might just one day turn around and realize you are now the teacher and you are mentoring others going through these struggles. You will never know it all just talk it out with your confidants and find yourself some mentors.