cold, wet soil with low air movement. i have a load of plants that have done the same. i have a bald bombay morich, chocolate hab, yellow scorpian, yellow 7 pot, chocolate bhut and a bald dorset naga. looks like a fatalii is ready to start shedding leaves now too. inca red is a bald fart now. all points to the loss of direct sunlight, stick your finger deep into the soil and see how if feels. i attempted to replant a scorpion to see if i could relieve the symptons with dry free soil and some ground seaweed but the twig is now yellowing.
you water with good intensions but all that is needed is a few of the dark cloudy days with no direct sunlight and your soil gets cold and stays damp. i thought of putting on a fan but the wife complains about the cold breeze.
good luck........... my plants have been in the house since september but once the snow hit and it hit early, it brought in those dark cloudy days that seemed to last for ever.