[shakna]

I am in no way an expert, which makes me very hesitant to answer these sorts of questions. I am a random person on the Internet. Take that into account when you read what I've written, and weigh it very skeptically.

My knowledge comes from my own health. I was diagnosed with fibromyalgia (which is probably not an autoimmune disease. Probably.), after a ten year long process. MS was the other diagnosis being considered at the end of that process. If I had lesions, MS, if not, FM. Because the latter leaves no physical traces that can currently be detected (there is some progress on that front, but one study does not a trend make).

Some illnesses do have a likelihood to be co-morbid with others. FM for example, has a large number of illnesses it often masks, which may mean it is more likely to have that sort of comorbidity, or it may mean that the statistical model to work out if it is more likely to occur is extremely difficult to create.

I can't speak to whether a disease being autoimmune in nature makes it more likely to trigger other autoimmune illnesses, but it wouldn't be surprising to me. A malfunctioning immune system can malfunction in unexpected ways.

[GordonS]

IME, many doctors, and even some consultants, use fibromyalgia as a catch-all where there is chronic pain and fatigue, but they can't find the underlying cause - basically a big umbrella to cover what are likely a broad spectrum of diseases and health issues.

I suffer from chronic pain and fatigue, and was previously diagnosed with fibromyalgia by both a rheumatologist and a neurologist, despite not even meeting the diagnostic criteria, and having an unrelated auto-immune health issue. Later on, via a skin biopsy I insisted on, it was discovered that I had small fibre neuropathy - damage to the small nerves responsible for pain signalling.

You didn't say anything about your specific symptoms, but if you have chronic limb pain, it might be worth looking at getting a biopsy.

[shakna]

> IME, many doctors, and even some consultants, use fibromyalgia as a catch-all where there is chronic pain and fatigue, but they can't find the underlying cause - basically a big umbrella to cover what are likely a broad spectrum of diseases and health issues.

That is very much not myself. I meet all the diagnostic criteria, and regularly experience somewhere around a hundred of the two hundred known symptoms. There is not another illness that matches my symptoms as well as fibromyalgia. I am a case study in what FM looks like at its very worst (literally, I've been featured in several journals as a case study).

I went through a variety of nerve studies before the diagnosis was made, and they're functioning perfectly. Including multiple biopsies. Getting the FM diagnosis is not easy where I live, most specialists would rather send you away with no diagnosis than that one. I met the criteria for FM on day one, and went through a decade of being tested for absolutely everything else.

The propensity for overdiagnosis, in some nations, of FM, causes me no end of pain whenever I raise the illness. There is always someone who feels the need to tell me that they believe it doesn't exist, or think that I must have something else that has gone undiagnosed, or think that they can suddenly cure it. That's exactly why I don't talk about it in detail. People think that they're helping, especially if they're empathetic. But all it does is undercut the last fifteen years. It makes the suffering more... Lonely. I can appreciate the sentiment, but I've never been able to appreciate the gesture.

I do expect that somewhere in the future FM will be split into several different types, and even illnesses. The illness is extremely "young", it got its name in 1993 (30-40 years younger than MS). Most of the illness is a total unknown at this point in time. There's no real global agreement as to what kind of illness FM is. It gets called autoimmune, neurological, rheumatoid, etc. depending on where you live. The evidence is currently leaning towards neurological, as FM has markers in the white matter of the brain that are unique to those who suffer from it. But we'll probably need another decade or two to be certain about that.