Hello Brian, I would check the condition of the roots. The container you used is also something I would not find suitable for it. Phal roots love lots of air around it. The media you used seems okay, but depending on your watering frequency which at this time should be of longer intervals to allow dry out time, so either there is root rot or collar rot.
Typically I would repot in a container with more side holes and putting the plant at an angle, and really be careful with watering during the cold months.
Also, is the plant still in bloom? If the blooms are already done, you can also trim down that bloomstalk so the plant can try and refocus its energies to root formation and eventually new leaves.