I see your plant came from California. It might just be that it has run through its growth cycle and is now dormant. Here in Washington State we are in the middle of the winter growing season but farther south things happen much sooner - and end sooner, too. Being as it is not actively growing you can very gently dig it up and look to see if there is an intact tuber. If so it will need to stored properly for dormancy until next fall.