This is most assuredly a case of mass hysteria. One sick passenger, with some illness resulting in marginal O2 sats, became hypoxic at cabin altitude. FA called a very compassionate nurse to assist, who administered O2 and solved the acute problem.
Second passenger in the vicinity of the sick one developed symptoms, which then spread to fifteen of the most suggestible pax, including the nurse.
The nurse did a great job, warm, caring, kind, obviously, but this is the situation where, unfortunately, one of these incidents is most likely to occur.
Nothing wrong with the pressurization, because they checked it, and because the masks did not deploy.
The moment I saw the nurse interviewed on TV, I was sure.