Rheumatism and rheumatology
Extremely rare diseases with vague or nondescript symptoms
The term "rheumatism" is recently back in vogue after long being used mostly as contemptuous term for various practices of medical quackery. And that is not surprising, since "rheumatology" in the meantime had always been considered a legitimate established branch of medicine. Doctors of that specialty had to have found a way to make a living on it somehow.
... SLE [systemic lupus erythematosus] symptoms vary widely and come and go unpredictably. Diagnosis can thus be elusive, with some people having unexplained symptoms of SLE for years before a definitive diagnosis is reached.
It's not adequately clear that a diagnosis like this is "definitive" at all of any specific disease or condition or useful to justify any particular care or treatment for it.
When RA [rheumatoid arthritis] is clinically suspected, a physician may test for rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs measured as anti-CCP antibodies). The test is positive approximately two-thirds of the time, but a negative RF or CCP antibody does not rule out RA; rather, the arthritis is called seronegative, which occurs in approximately a third of people with RA.
A "rheumatoid factor" offering so many false positives and false negatives for a presumed diagnosis is useless, and there is obviously no "gold standard" to measure it against. People often do have trouble with their joints when they get older, but nothing specific is being offered as a care or treatment for a diagnosis that is little more than a guess. Whether or not the said "rheumatoid factor" determines whether a person's arthritis is of the "rheumatoid" type or not.
Once again, there's a peculiar established medical specialty with a highly protected turf and all-but-guaranteed stream of income from practicing it.
What happened to the miracles of Jesus? The halt and the lame aren't walking here, two thousand years later with all the advances of modern medicine. Supportive care and some symptomatic treatment are essentially all that can be offered without any particularity or specificity of diagnosis of aching joints. Regular gentle to moderate exercise and especially swimming might be more helpful than the excessive doctoring and drugging in some cases.