This is an absolutely great description. What I think is hard for most people to understand is that we have no idea what's going to be wrong next. Will it be fatigue, will it be aching legs, will it be muscle spasms, swollen parotids, dry eyes, etc. I think if we had consistent every day symptoms in one(maybe two)areas it would at least seem like there really was something physically wrong.
You just don't know and you can't always predict what's going to be wrong today, tomorrow or the next day.