I know what you mean about trying to focus and not being able to. When I was working, I did the training of all the new hires. I had to tell my boss that I couldn't do training in the evening anymore because I couldn't focus on what I was trying to teach these people. I hadn't been diagnosed with FM yet, but I think I've had this for a long time.
I hope things get better for you. Remember, we all know what you are going through.
Have a great day