Leather coral dying?! Advice please!

[Loko]

I bought this small toadstool about 2 1/2 weeks ago. The first picture is when i first got it. It was curled up and it looks at though it was already trying to split into 2? I didn't get any before pictures of when it opened. After about 4-5 days of having it, i went out of town for 6 days. During those 6 days, my power was off for at least 18 hours. I was unable to get back for a water change until 4 days after this incident. My fish, (2 chromis, 2 clowns, 2 purple firefish) are doing 100% normal after the water change, as well as the hammer coral and 2 zoa colonies i got 3 weeks ago. After i did a water change the polyps have been out as visible in the photos. It looks like it was rotting from the middle, and along the edges of this "rotting" the coral is neon yellowish. I guess what i'm looking for is a possible cause for this "decay?". And is there a way to save it as a whole? should I cut it up and frag the healthy looking pieces? Thank you in advance.

Before

After

 

[Loko]

So this picture was taken about 1 hour after original post, (roughly 30 hours after water change). It went back to being all droopy after about 10 minutes.
But notice the, what i think is a Waving Hand polyp, in the photo. Would that be the culprit?

 

[Tzwizzle]

So from my experience sps rtn, LPS recede, and softies wither away like this. I dont think the small polyp did this. Could be a lot of things such as flow, light, unfavorable conditions or water quality. Or maybe it was just diseased. I've tried fragging a couple leathers that looked like this in an attempt to salvage them with no luck.

 

[garygonzales]

it looks like it was just ****ed of from water change...maybe wasnt the same temp ..salinity...etc.....also leathers tend to do this ...it will get all swiveled up and shrink...for awhile...and then be back to normal....make sure it has some flow too..this would help with the shedding process...

 

[Daniel62]

Yes, they seem to like quite a bit of flow

 

[justthewife]

They like good flow but not direct and I believe they are also sensitive to alkalinity. What are your parameters? What kind of toadstool were you told it was? It almost looks to me like a sarcophyton which may explain the yellow color.