| I'm wondering if your beloved plant is a Croton (Codiaeum variegatum). The brown bits - roots perhaps, might have developed rot. I'm puzzled about why the plant would fail to drain with all the care you've been taking. Possibles: the drainholes are blocked. (New pot needed perhaps - but you might need to downsize if the plant actually has got root rot.) The soil structure has broken down and the original drainage has closed up in the pot. A change of soil is in order. The plant is in a cool spot and it's not pumping water fast enough to dry out the mix it lives in. The roots have been dying back - or entering a rest phase - for a while and they're not active enough at the moment. (Older roots may be brownish. Dead roots are often 'flat' in appearance and break off very easily. They sometimes look almost transparent. New and lively roots can be cream or white - particularlyat the tips.) You could put it back into a warm and bright place with enough pebbles in its saucer to let the air get underneath and the last of the drenching to go. After that, your usual winter care will probably be enough. (Water once a week or less - just enough to keep the mixture from drying out completely.) Do check out that the drain hole/s are free of roots. | 
