Gwenllian-- Chicken pox/shingles is nothing to sneeze at, despite the comical name. It is due to a nasty virus that lies dormant in the body pretty much forever; it comes out to play when the immune system is compromised, which means that most of us are potential playgrounds.
Nasty, brutish, and painful, to adults, in my experience (I had childhood chicken pox, but don't remember much about it.) A hot aloe bath I found to give temporary relief, but it was still a wasted few weeks, when I couldn't do much to earn my keep. It wasn't fatigue, exactly, but more of an inertial impediment. Once I got moving, I could keep moving; when I sat down, it was too easy to keep sitting. I think if I were a depressive sort, I think I would have been a basket case. I'm not; even so, there was a definite funk that was hard to break out of. (One thing that is pretty much a permanent fixture of my personality is to rant at things I consider stupid--in current events, politics, and so on. That I couldn't muster enough juice to care enough to rage was telling. Even more was the fact that this didn't worry me!) I do not know how to advise you specifically, as everyone is different. For me, immersing myself in writing and cooking and fetching coffee for my wife took the edge off--enough that I could become professionally (and even socially) productive again in less time than the medical pundits had given me.
Pain can be serious, both directly and indirectly. Please take care of this part of yourself! I'm not sure about a blast of prednosone, or prednisolone. True, in a big pulse, you might feel like a million bucks, for a short while. But you can't keep taking it at that level, and the virus can keep on offending for a long time.
And keep the reports coming! They can be good therapy as well.
Al