Hi lorrapaw - it's one of those supplements for which there is insufficient evidence as to its benefits. Anecdotal evidence from individuals therefore is not really a sufficient endorsement to warrant taking it, I would say.
Here is an impartial summary of its known effects and what research has shown:
http://www.webmd.boots.com/vitamins-and-minerals/coenzyme-q10-coq10 It has not been approved by US FDA for the treatment of any medical conditions, nor has the European food regulator approved any health claims for it. As far as I can gather research is ongoing.
Are you post-menopause? Also do you take HRT at all and have you had thorough hormone testing to look into the possible causes of your fibromyalgia - including sub-clinical but symptomatic hypo-thyroid problems, oestrogen deficiency due to menopause, low testosterone and possible vitamin or mineral deficiencies which can cause aches, pains or fatigue? It is worth exploring every avenue to help with such debilitating lack of energy!
Hurdity x