Have you tried googling fibromyalgia? This is basically what I found
"Symptoms of FM
As well as the chronic pain, including skeletal pain, and tenderness, some or all of the following symptoms might be present:
Neurological: dysfunctions of muscles, ligaments and joints – numbness, tingling; abnormal muscle twitch response, muscle cramps, muscle weakness; headaches, generalised weakness, dizziness, and sensory overload.
Neurocognitive: These are usually present and include: impaired concentration and short-term memory problems, impaired speed of performance, inability to multi-task, one is easily distracted, and/or cognitive overload.
Sleep disturbances: Like ME/CFS sufferers, most people with FM experience nonrefreshing sleep. This is usually accompanied by insomnia, frequent nocturnal awakenings, nocturnal muscle twitching, and/or restless leg syndrome.
Autonomic and/or neuroendocrine: These include but are not limited to: cardiac arrhythmias, neuraly medicated hypotension, vertigo, temperature instability, hot/cold intolerance (intolerance to very hot or very cold weather), respiratory disturbances, irritable bowel or bladder dysfunction, dysmenorrhea, loss of adaptability and tolerance for stress, reactive depression.
Stiffness: Generalized or even regional stiffness that is most severe upon awakening and typically lasts for hours. Stiffness can return during periods of inactivity during the day.
As with ME/CFS, symptoms can vary over time with the waxing and waning over periods of hours, days, weeks, months and so on. An increase in stress can cause a worsening of symptoms.
What Causes FM?
The cause and/or causes (known in the scientific literature as the aetiology or etiology) of FM are unclear. Like ME/CFS the trigger for FM may be different for different people. Before the onset of FM, most people enjoyed an otherwise healthy active lifestyle.
There is evidence that a physical trauma, such as a spinal injury or whiplash can trigger FM in some people. Other associated physical traumas include surgery, repetitive strain, childbirth, viral infections and chemical exposures. Emotional stress may also trigger the illness. Some people may be genetically predisposed to FM, especially when more than one family member is affected. Some cases of FM have a gradual onset with no obvious cause.
The result is a change in the way the body “talks” with the spinal cord and brain. Levels of brain chemicals and proteins may change. For the person with FM, it is as though the “volume control” is turned up too high in the brain’s pain processing centres."
I have posted all that as it seems to me this is in fact a recognition of the generalised nature of autoimmune dysfunction being seen in various parts of the body. But the diagnosis is concentrating on the generalised pain side of things rather than the inflammation, which the psoriatic arthritis diagnosis recognises. It is the brain and pain side of things that a fibromyalgia diagnosis recognises.
But that website goes on to say something that I personally find very disturbing. Here it is
"How Is FM Treated?
At this point in time there is no known cure for FM. However, symptoms can be treated with both medication and non-drug treatments. An effective management program should be designed to suit the needs of the individual.
Generally, management of FM will involve a combination of:
Education – people with FM need to understand as much as is practicable about the condition in order to decide which management approach will help them. Keep yourself informed.
Medication – combined with other strategies, medication may be used to manage pain, reduce stress or promote sleep. Please also see our page on Sleep – including sleep hygiene.
Exercise – a gentle aerobic exercise program, such as walking, tai chi or water-based exercise, can help to manage symptoms such as pain, fatigue and sleep disturbance. Please see our page on Exercise (Graded Exercise Therapy).
Relaxation – stress may aggravate symptoms. Skills that can help manage stress include planning, relaxation, assertiveness and emotional management.
Pacing – balancing rest and activity, plan your activities to make the most of your energy by alternating periods of activity with rest. Break large jobs down into small achievable tasks so that you do not overdo things. Please see our page on Pacing.
Massage of one form or another – this can aid muscle relaxation and stress management.
Nutrition – eating a balanced diet can help provide you with better energy levels, help to maintain your weight, give you a greater sense of wellbeing, and give you a sense of control over your life. Identify any potential food intolerances."
I may be wrong, but it seems to me after reading this that a diagnosis of fibromyalgia is an excuse to not prescribe anything particularly helpful. Just pain management. And there seems to be no real understanding of cause related to this diagnosis. The website says that there may be genetic causes and environmental triggers. Really! Can you see any difference here with what is said about psoriasis and psoriatic arthritis?
As it seems you have had problems with immuno-suppressors already, I would ask you to please try the last little bit of all that generalised guff for fibromyalgia treatment, and look at the possibility of food intolerances. Whether what you have is fibromyalgia or psoriatic arthritis is only a question of how widespread your symptoms are, and if it is the former, then your problems are already widespread.
Have a look at what I have said about diet and FODMAP. Eliminating inflammation causing foods has sorted some of my problems, especially pain. I have eliminated the brain fog, I sleep better, and no longer have reflux, asthma or irritable bowel problems.
Oh and lastly, my personal preference is that the whole diagnosis of fibromyalgia be dumped in favour of something recognising the autoimmune and inflammationary nature of the problem. Perhaps something like "subclinical lupus" might be better. But that is just between us. Don't tell your specialist. They have many years invested in their knowledge and will undoubtedly not take kindly to any lay person thinking they know better. Do I know better? Maybe not, but I have a different perspective. I suffer from all this, what for the specialist is just someone else's problem.