I'd like to welcome you here to the Forum along with Petal22.
Going from being a confident driver, something you realy need in your life, to someone who feels they can't handle the heavier traffic is a horrible way to be. It makes things so frightening and difficult and I can understand the urge to call in sick to avoid the problem.
I guess there are two things to think about, the first is there any change that has made you reactions slower, your eyesight not as good, your hearing less or some other purely physical problem you have not realized?
The second is the anxiety you mentioned, and if it not only causes your life to be miserable but ruled by it then it needs to be addressed. Plus if it makes you over-react on the road getting relief is most urgent.
My apologies if you already have things in hand however can I suggest that you visit your GP in a long consultation and get both a thorough physical examination and most importantly also talk over your anxiety and how it is affecting your life.
I found (I have an anxiety condition together with other things) that once it started to become more severe I could do nothing to make myself better and lost confidence in the normal things I did. In fact my condition deteriorated until I started to receive the proper medical help with therapy and in my case medication too.
That was the start of a great improvement, not instant, but I am now nothing like I was before. I was frightened to perform many tasks for fear of failure, now they give me satisfaction.
May I ask if you having to face this all alone or is there someone in your life you can talk about this with, who may not be able to fix things, but listens and is there for you? It can help a great deal. I was blessed to have a very capable and loving partner, and when I finally said what was wrong it seemed like a load had been lifted off me.
Please come back and say what you think