Trachyphillia Dying? Flesh turning brown and white and decaying?

[Herides]

Sure thing. Always my pleasure!
Yes, applies to wellso as well. Again, low light and low flow is important.
They will on occasion "poop" zooxanthellae out the and what you described sounds just like that. They will tighten up and exude through their mouth the zooxanthellae every so often. Nothing to be concerned about.
You may want to get a par meter and check your lighting intensity...

I might move him somewhere darker then as he hasn't inflated again since. I have a seneye tracker for my tank and those have a built in par meter so at some point I'm gonna recheck my pars around the tank.