Strong light and good air flow are the best options if you suspect a fungal problem. Avoid milk or other home remedies that may contain food for the microorganisms. I would also avoid fungicides because any treatment is likely to lead to relapse in the absence of changes to the environment (light, air flow).
One thing that works great against various pests is 70% alcohol delivered from a spray bottle on the surfaces of the plant. It dehydrates exposed organisms without affecting the plant much, and then evaporates away afterwards.
I realize that now is about the worst time of year to dial up the light, but do what you can. As much light as possible indoors, like right by your sunniest south facing window. It is basically impossible to provide too much natural light for a jade indoors, given mild temperatures.
