While the jury is still out, some studies have indicated that CFS "does" exist and may be an autoimmune disease, on its own.
The ME hummingbird website states the following:
It is important to be aware that Myalgic Encephalomyelitis and 'CFS' are not synonymous terms. Myalgic Encephalomyelitis is a distinct, scientifically verifiable and measurable, acute onset, organic neurological disease. ‘CFS’ in contrast, is not a distinct disease. ‘CFS’ doesn’t exist. Every diagnosis of CFS – based on any of the CFS definitions – can only ever be a misdiagnosis.
Chronic Fatigue Syndrome is an artificial construct created in the US in 1988 for the benefit of various political and financial vested interest groups. It is a mere diagnosis of exclusion (or wastebasket diagnosis) based on the presence of gradual or acute onset fatigue lasting 6 months. If tests show serious abnormalities, a person no longer qualifies for the diagnosis, as ‘CFS’ is ‘medically unexplained.’ A diagnosis of ‘CFS’ does not mean that a person has any distinct disease (including M.E.). The patient population diagnosed with ‘CFS’ is made up of people with a vast array of unrelated illnesses, or with no detectable illness. According to the latest CDC estimates, 2.54% of the population qualify for a ‘CFS’ (mis)diagnosis. Every diagnosis of ‘CFS’ can only ever be a misdiagnosis.
However, while 'CFS' is not a genuine diagnosis, those given this misdiagnosis are in many cases significantly or even severely ill and disabled, with conditions including:
Various post-viral fatigue states/post-viral fatigue syndromes (eg. following glandular fever/mononucleosis, hepatitis, Ross river virus, Q fever, flu, measles, chickenpox, herpes and many other infections)
Fibromyalgia
Candida
Athlete over-training syndrome
‘Burnout’
Multiple chemical sensitivity syndrome (MCSS)
Multiple sclerosis
Thyroid illness
Adrenal insufficiency
Localised and Metastatic malignancies
Brain tumours, including astrocytomas, gliomas
Transverse Myelitis
Myopathic illnesses including: Myasthenia gravis, Mitochondrial myopathies, Post-infectious polymyositis
Vitamin B12 deficiency disorders: Pernicious anaemia, Intentional dietary deprivation, Intestinal disease associated with or independent of M.E.
Rheumatoid illness or lupus (SLE)
Sarcoma
Renal or liver disease
Infectious illnesses including: Toxoplasmosis, AIDS, Lyme disease (Borrelia burgdorferi), Tuberculosis, Brucellosis
Various psychiatric and social psychiatric states including: Anxiety neurosis, Uncomplicated endogenous or reactive depression, Clinical depression, Psychopathic personality disorder, Post-traumatic stress disorder (PTSD), Schizophrenia and other psychiatric disease.
I'm assuming that the smaller nodules on the left lobe of your thyroid, which you say are "not yet visible", were seen on a thyroid ultra sound? That would be the only way to know they are there, if they can't be felt via palpation, unless your doctor is guessing.
Many of us have nodules on our thyroids, which are not issues, so the smaller ones on the left lobe may never cause problems.
Postural hypertension (hypotension) is a sudden drop in blood pressure when standing up from a sitting or lying position, which can range from mild to severe (passing out); it can be caused by a number of things, including diabetes, dehydration, heart problems or other nervous system disorders. It could be related to the CFS, but I haven't seen anything that would relate it, specifically, to a thyroid nodule or cyst.
It's possible that the cyst is causing issues with your thyroid hormone production, possibly causing you to be hypothyroid, which has similar symptoms to CFS. Hypothyroidism can cause low blood pressure/low heart rate.
Do you have any current thyroid hormone blood test results that you could post, along with reference ranges?
Regarding alternatives, I don't know of any; it appears that your choices may be limited to the partial removal, or maybe you'd want to opt for total removal, to insure that you wouldn't have to have another surgery.