A friend posted this over on her home forum today (LupusUK if anyone is interested).
Now I know it says Sjogrens but that doesn't matter. The fatigue of autoimmune disease doesn't vary THAT much but Sjogren's is said to be the worst. I don't know, there are degrees of everything and although I suffer from dry eyes there is little indication I have anything more than that but the No 3 Sudden fatigue - I get that. Suddenly, out of thin air, I feel nauseated and just want to die in a corner. Next morning i'm fine.
So - read, mark, learn and inwardly digest. Maybe it will help you identify why when you feel rubbish.