I have always been pretty healthy and fit, but suddenly, in my mid 40s, feeling a bit like my body is letting me down. I have been feeling very tired, and although I have busy life, this feels like more tired than normal. But what is really concerning me is that I had some severe pain in one part of my upper back recently. After a couple of days the pain moved to a different area and then again to another area - but it was so bad I had trouble getting out of bed. But then the pain suddenly disappeared and I am wondering whether this was nothing to do with too much sitting down (as my physio suggested) but more related to my tiredness. I have been very stressed, depressed and run down over recent years. Could it my something like chronic fatigue syndrome or fibromyalgia?