i dont know if you already got your answer and it worked, but regardless.....leaves yellowing and drooping, soft to the touch, and can be picked off the plant by the slightest touch means lack of water, and the best thing to do is water them.....make sure your room temperature is 75 or up a little water thoroughly......the only other things that could cause the specific defiency you are describing is to much heat(but the leaves wouldn't be yellow, or too cold(in which the leaves still wouldnt be yellow). it's your watering........it's not enough......