While FND/CS Syndromes like Fibromyalgia, Chronic Fatigue Syndrome and related, are most commonly viewed as nervous system conditions (windup - central sensitisation syndromes), it is important to remember that the nervous system (nerves, spine, brain) does not work in isolation and that what is going on in the body (e.g. cells, liver, gut, infections) and with other systems (e.g. immune system, hormone - endocrine system) impact the functioning of the nervous system and mind and vice versa.
While doing things to support the mind and nervous system (anxiety management, relaxation, therapy as needed) is very important, it is also important to consider what is going on in the body and the impact your lifestyle, dietary choices, and the environment around you is having on your body and mind. In recent years this has been acknowledged and as such a more comprehensive multidimensional approach is now being promoted.(e.g pain recovery programs and self management), to people with persistant pain and fatigue, rather than just psychological therapies!
While these help address the common underlying causes (mind and body) that promote ongoing issues, this is not enough for everyone. E.g people with more severe severe Chronic Fatigue Syndrome, Fibromyalgia and many related functional pain syndromes - Central Sensitivity Syndromes.
Irritable bowel syndrome and other gastrointestinal (GI) and non-GI disorders such as functional dyspepsia, fibromyalgia, temporomandibular joint disorder, interstitial cystitis/painful bladder syndrome, and chronic fatigue syndrome are known as functional pain syndromes. They commonly coexist within the same individual. (1)
If standard treatments and self management does not work well for you, or aggravates and worsens symptoms, like they did for me. It is in my opinion and experience, helpful to identify DOTS and other things that contribute to what I call LINGHER issues. These things often go together.
LINGHER stands for
Liver (sluggish, injured, impaired)
Hormones (outside normal range e.g. cortisol, thyroid)
Energy Making (high oxidative stress, other impacting mitochondria ability to make energy)
Regulating Sensory Stimuli impaired.
Unfortunately Lingher issues are not generally picked up by standard pathology tests. Rather they are assessed for by skilled practitioners that consider your exposure history and perform alternative tests, e.g. allergy testing, functional pathology tests. Not all doctors do. They can be costly!
While you can go from one health professional to another picking up clues, which is what I did for many years. An easier approach, (now available) is to consult with a doctor trained in the Functional Medicine Matrix or similar. Usually doctors trained in Functional medicine or Nutrition and Environmental Medicine (NEM) or Integrative Medicine, who have a good understanding of complex multi system health issues.
(1) Overlap between functional GI disorders and other functional syndromes: what are the underlying mechanisms? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812246/