A while back Candida aka chronic candidiasis and several other names was a somewhat popular fad diagnosis. It was supposedly responsible for just about any symptom you can imagine. It was especially invoked to explain non-specific symptoms like headache, fatigue, joint or lower back pain, irritability, mood swings and other such symptoms that many people experience in their lives and can be caused by many conditions or emotional and mental stress. Candidiasis hypersensitivity is one in a long line of dubious or non-existent conditions invoked to explain these sorts of non-specific symptoms. Given the extremely broad range of symptoms, pretty much anyone could be diagnosed with it. Actual clinical evidence of Candida infection strictly optional.
Candida woo woo has kind of gone out of fashion but it still has its adherents and advocates. Candida can cause health problems (most commonly candida vaginitis) but candidiasis hypersensitivity syndrome isn't a valid diagnosis or a real condition.