orchid turned for worse :(

[quiltergal]

If it were mine I would not seal it up in a plastic bag, you risk rotting it. I only do that (with limited success) on absolutely rootless plants which this one is not. You will lose the bottom 3-4 leaves no matter what. They are too far gone to be saved. However, if the newest leaf looks good and firm the plant will most likely be fine.

The pot looks exceedingly dry to me. I would do as silken suggests and put a bamboo skewer into the center of the pot and leave it there. Pull it out to check for moisture. Phals like to be evenly moist, and I fear you may have overcorrected by underwatering.