Specifically, one of several invented diseases that a London quack, "Doctor" Tufts, claimed around 1670 to have an infallible cure for. For a while after him, mountebanks claimed to be able to cure these as well, until new fads buried the old and they survived only as footnotes in books about curiosities of medical quackery. That is, until Dorothy Dunnett and Patrick O'Brian resurrected them as period detail in their historical novels, leading to a minor flurry of amateur scholarship trying to figure all this out. For a usage, I can give nothing better that Tufts' boast:
Now the names of these new Distempers are the Strong Fives, the Moon-pall, the Marthambles, and the Hockogrocle. Although the Names, Natures, Symptoms and several cures of these New Diseases are altogther Unknown to our greatest Physicians, and the particular knowledge of them would (if conceal'd) be a vast advantage to the aforesaid person; yet he, well knowing that his country's good is to be prefer'd to his private interest, doth hereby promise all sorts of People, a faithful cure of any or all of the Diseases aforesaid, at as Reasonable Rates as our modern Doctors have for that of any common Distemper.Well that convinces me -- sign me up.
As soon as someone comes up with a good summary of the symptoms in the comments. Be as creative and convincing as you can.