Can I resuscitate a drowned plant?

Can I resuscitate a drowned plant?

I received a Christmas cactus in December and it's been doing pretty well. It was putting out new branches almost daily and while it hadn't bloomed at all I attributed that to the fact that it's pretty warm here (coastal NC). Anyway, I recently read that they need indirect sunlight for best growth and as we don't really have anywhere near a window to set the plant without it receiving direct light, I put it out on my back porch last Monday once the sun was around the end of the house. Long story short, I forgot the plant outside and it poured rain that night. Now, over a week later, the soil is still damp (prior to this incident I'd had to water it once every three-four days) and now small, chalky looking spots have started showing up. They're white, about the size of a pencil eraser, and wipe away with just my finger. But then the next time I check the plant the spots are back. Any idea what the spots are? And, have I ruined my plant?
corn rejects

corn rejects

Desert Botanical Gardens

Desert Botanical Gardens

Shifting Hybrid Teas

Shifting Hybrid Teas

im new.

im new.

Pansies

Pansies

Happy Independence Day, American Gardeners!

Happy Independence Day, American Gardeners!