From my understanding...I could be mistaken -
For wc you have to be able to prove that something at work caused the injury or condition.

Was there any type of injury before the Fibromyalgia occurred?
Do you have a firm diagnosis of Fibromyalgia and possibly with a few drs agreeing?
Does your dr believe your job caused the Fibromyalgia and can /will he be able to explain how & why?
like possibly - chemicals, repetitive injuries, other - I'm not sure what else may cause Fibromyalgia...

Another thing that might come up - were you healthy before the fibro occurred or have you had misc health issues in the past - these might have lead up to the Fibromyalgia.

We do have a Work comp forum ( http://neurotalk.psychcentral.com/forum30.html )
as well as Disability forum ( http://neurotalk.psychcentral.com/forum28.html )
- both of those might be helpful with tips on best ways to proceed in the various "systems".