[A] change in one's way of life resulting from penitence or spiritual conversion: "what he demanded of people was metanoia, repentance, a complete change of heart."
Enantiodromia:
[T]he tendency of things to change into their opposites, especially as a supposed governing principle of natural cycles and of psychological development: "the remorseless enantiodromia between good luck and bad."
It seems to be way more than a "flip".
When someone's entire personality and cognitive abilities seem to have changed, that's not a flip. That's something else......
Metanoia:
Enantiodromia: