Yesterday I was doing my "check" of my hoyas and discovered my kentiana had turned all yellow on top and that the leaves were falling off the stems. In fact, I now have a couple of bare stems. I tend to underwater and we have had NO sunshine in I can't tell you how long. It is sitting in a room with a warm air and cold air humidifier running alternately. Should I add some fertilizer and water a little bit more. I'm just in a frantic and am not sure what to do. It has been doing so well and it seems like this happened all of a sudden. I do apologize if this question has been asked before...Any ideas/suggestions would be greatly appreciated.