Bodhi Plant Wilting

I have a potted bodhi plant that I brought with me when I moved from Florida to Ottawa 2 months ago.
Initially older leaves yellowed and fell off. I thought perhaps the dry indoor air and lower light would be a problem, but then it began very rapid new growth, at almost 3 cm a day.
However, in the last 5 days, those new leaves and tender branches have all wilted (without yellowing) and have been falling off. They first darken, perhaps shrivel a bit, and then wilt and drop (even branches).
The soil has moderate moisture, as usual, and there are no obvious pests. What am I missing?

This sounds like a plant growing in far too little light. It therefore produces elongated (etiolated) growth that is very weak, soft and very susceptible to fungal or bacterial attack. The darkening of the stems sounds like a fusarium infection to me. You can try increasing the light substantially with artificial lights and hope that the fungus has not killed the whole plant yet and hope for new sturdy growth.