By the definition given in the Disability Act -Fibromyalgia is a disability and recognized as such, and just because the signs and symptoms aren't visible to every one else doesn't make it less so,we therefore under the Equality Act are as entitled to help as much as anyone else, doctors ought to be aware of this--it may mean things like modifications to your home or working environment doesn't always have to be claiming an allowance,worth discussing with your doctor.
Sorry getting to tired to concentrate.