I am having problems with my Christmas Cactus. It used to be very healthy, and in fact, bloomed in both November and January (see first picture). Now, pieces of it keep falling off and it doesn't seem to be taking water very well. (see second picture). The pieces on the edges of the plant are parts that have fallen off and I've put them back in the soil in hopes that they will take. The third picture is of the stem where it seems to have become woody at the soil line. This is the part that keeps loosing pieces and doesn't seem to be taking water well. Help!!