I've had it over 5 years now. It came out of nowhere for me, one night just sitting sewing on the sofa when I suddenly felt like someone had poured cold water down my back. By the next day my skin was on fire and my limbs felt so heavy. They also ached and burned with lactic acid from things as small as pushing down a door handle or reaching up to take something down from a high cupboard in the kitchen.
It all happened so fast that I was worried I could be developing MS, so went straight to the GP. MS was quickly ruled out, and full blood panels - several of them, at different points - show nothing. I have no inflammation, no deficiencies, no muscle markers that would point to a problem. Seemingly, there is nothing 'wrong' with me at all, yet I experience problems with speech (slurring, stuttering, absolute random nonsense coming out of my mouth instead of what I intended to say), my bones ache, I am stiff and sore, I cannot bear any pressure on any part of my body because it causes intense pain and pins and needles. I wake up a thousand times a night because it is so painful to lie under my own weight. I now have to use an NHS-provided bath board in the shower so that I can wash myself without having to stand up and lift my arms over my head. My limbs constantly go numb. I experience crushing fatigue; even my face feels exhausted if I smile too much. I can pull a muscle for days just by taking a phone call and having to hold the phone up to my ear for a period of time.
I was part of a coping skills programme after diagnosis which involved correspondence with a physiotherapist and occupational therapist. One of those explained that one of the reasons it is believed that people develop fibromyalgia is because intense stress, PTSD, anxiety or other mental health problems, and constantly being in fight or flight mode, causes the nervous system to become permanently stuck in the 'on' position, and starts interpreting perfectly normal input as pain. This certainly fits for me.
I have absolutely no chance of working. I do receive some benefits since I did the WCA and they said I wasn't fit. But that's a whole other kettle of fish ...
I agree that fibromyalgia is a diagnosis based on elimination, and one size isn't really going to fit all - it's not as cut and dry as a lot of other conditions that often have quite a specific set of symptoms. But for me, yes, it is very real.