you might want to re post this over in houseplants. My guess is that soil is staying too damp for the roots. I would remove the plant an do a complete repot with a faster draining mix and at the same time check the root health.

Sans,

I was thinking the same thing. Most plants do well in a more freely draining soil so the roots can breath. It may be too late. Hope it goes well for you.

Stush