Coping with fatigue is hard because with fibro, your tired when there is no reason for it or because of being in pain, or not sleeping well. I find when the heavy fatigue sets in it is best to take it easy and not plan to many things during those days. Like I babysit for a relative one day, so I only do that on that day. When he goes home, if I am able I do light easy work, nothing to increase the fatigue.
Sometimes the fatigue comes from to much pain and it over-whelms our bodies and makes sleeping hard, as in nothing is comfortable. Take pain medication for the pain and to help you sleep better get a fiber or feather bed topper. They come in all sizes from twin through king. It makes the bed softer in regards to your muscles but provides enough cushion if you have a bad back. I have used one for years as before I could not even sleep on a water bed because it felt to hard. This 3" thick pad lays on top of your regular mattress and can make sleeping a lot easier.
If you sleep better you will have less pain and fatigue. If all else fails get sleeping pills from your doctor for those rare nights when nothing else works.
Often times we think because we fall directly to sleep that we are sleeping well. But if your still tired when you wake up then you need to consider the above coping ideas. You also need to be patient with yourself and understand that your ability to muli-task has been lost by the coming of fibro and taking an easier approach to your days will help you in the long run.