Ahhh Yabbity One!
That was one of my worst ongoing complaints. The only thing that ever helped was steroids and sleep, often together! It would happen in stores, at work, when I was driving, when I tried to concentrate on anything that required brain cells to work!
You are going through a lot right now and that only makes it worse. You need to learn how to grab every shuteye opportunity possible, even if it's only 15 minutes!! Honest to god it helps, and it's truly the only way to cope with it. You also may need a course of steroids.
My silly younger bother ( and yes I spelled that right!) told me to either GET some rest or take it as a cheap high! It was the only time he has made sense in years!!!

I did both...