Can chronic fatigue syndrome come on suddenly? like one day i'm fine, the next i wake up and can barely move arms and legs? would prednisone help cfs?

CFS hard to treat: CFS is not well understood, but symptoms do occur suddenly or fluctuate. To fit criteria for CFS symptoms have to be ongoing for 6 mos and have features like memory/focus problems, unrefreshing sleep, sore lymph nodes. Steroids like pred help some, but these drugs can have bad long term effects. There is not a proven treatment or cure. Make sure your doc has ruled out other causes of weakness.