Specific worsening of fibro symptoms

Hi, I've posted elsewhere before but something has been happening that's been impairing a lot of things and it's irritating because I can't do things that I want. My chronic fatigue has been worsening over the past 6 months and I've got a "new" symptom (I say new in quotes because it sometimes happened anyway, but now it's regular) - when I move my arms, I often feel they're really weak and I feel nauseated. I *can* still move them, but the after-effects of moving them for a little while (as you might tend to do) are unpleasant. Is this just due to lack of activity? What should I do to try and make things easier for myself? Thanks in advance.