Please help, bubble coral sick

[HeavyShev]

Hello, my bubble coral suddenly retracted completely on one head. It was fully extended before, and now that head looks sucked in.

The only recent change was a temperature swing—my AC went out and it went from a steady 77 up to 79.8. I also slightly lowered my light, but flow has stayed the same.

Current parameters are stable and within my normal range: salinity 1.025, calcium 440, alkalinity usually 8 (briefly dropped to 7), magnesium 1400, phosphate .04, nitrates around 5.

What concerns me is I had a torch coral do the exact same thing about three months ago—it retracted, I tried dipping it, and it eventually bailed its tissue and died. I’m worried this might be heading the same direction.

All my other corals look healthy. I’ve left this one alone so far, but I can’t tell if that head is still alive.

Any idea what could be causing this, and if there’s anything I should do or just wait it out? See pics.
Thank you to anyone who responds.
J

 

[DSC reef]

Im wondering if you have some coral warfare going on, keep an eye out for sweeper tentacles from the other euphyllia, they can reach over 6" in some instances. Parameters seem ok, minor temp swing isn't concerning and since the other corals look good I'm leaning to some coral battling going on.

 

[Mr. Mojo Rising]

I think your corals are too close together, I would give them a good 6" to 8" of space to be safe