Leaf shedding on otherwise healthy (I think) plant

[diaphainein]

Hi everyone!

I need some help. I have this orchid I got from a co-worker, who was going to throw it out because it had stopped blooming. I have no idea what kind it is.

On Friday night (February 18th), all its leaves fell off. Nice, green, healthy leaves, with no yellowing or other discoloration. They just (literally) shot off the plant--I found them a few feet from where I keep it (on my mantle where it gets a good amount of sun--I face North/South and all I get is indirect light).

I usually water about once a week and check the substrate for dryness before I do. This guy was quite moist when I removed it from the soil (today just a few moments ago) and the areas where the leaves were are now black.

Have I killed it? I live in Dallas, Texas, and we've had some weird weather lately. In the past two weeks it has snowed for four days straight followed by a week of 70-80 degree weather and now it's back in the upper 40's. I try to keep the temperature in my apartment fairly consistent, and keep my thermostat at about 72 degrees.

Please let me know if there is anything I can do to save it. This is the first orchid I've actually done well with.

I brought photos to help, too.







(what are these shoot thingies I'm pointing to?)