What is the temperature of your tank water?
Are you dosing Iodine?
Unfortunately, many times, Xenia will die off and to no understanding as to why! The good thing however, is that as quick as it dies, it can come back and grow...
Maybe it is a direct result of your doing excessive water changes...or too little light, or even the collaboration of doing to much to soon!
Sorry to hear about your Xenia loss.
I know last March when I went on vacation, my Xenia was doing awesome. When I got home a week and a half later, they were not healthy, as evident by the color variance and their becoming smaller and also not pulsing. I did the same things as you did to try to rectify the problem! After several attempts of saving my Xenia colonies, I noticed that I had salt creep on the protective glass cover of my halide pendant! So, after cleaning the cover with vinegar, a few days later and all was back to normal as they all rebounded and have since grown more.
Best of luck and hope that your last Xenia makes it to regenerate for ya! _________ 125gal.w/Mag9.5 return(dual megaflow)>Mag7 pump Aqua Cev180skimmer.Wave2k Hamilton Reefstar(2)250watthqi(mh)pend.a Yellow, Naso Tang Red Lip Blenny Percula Clown Demoiselles Niger Trigger F. Wrasses Ceriantharia Orn.Shrimp and Stars Hermits Queen Conch asst. snails> Stars Zoos shrooms Montipora Brains Gorgonians Favia Turbinaria(large+small polyp) Acropora Xenia Tridacna (CroceaMaximaSquamosa) Leathers <35+75gal.reef tank as well> 
"IF THE PHONE DOESN'T RING...IT'S ME"  jb  | 
