Update? Hope all is improving! I have been through something similar twice. It turns out it was chemical both times. The first time I found out when my mother fessed up when she and my father were looking after the tank (it broke my heart with what I lost that time). The second time my husband suspects he may have caused it and I didn't know until it was much too late.
Vitamin C helps zoas come back also! Another board I am on, started experimenting, and I added it to my tank, and it helped a lot of my polyps to open and start growing. Here is the link, and you can read it for yourselves! I have had good success with this so far. http://www.uberfrags.net/forums/showthread.php?t=1648
Someone sprayed a ton of airfreshener on a carpet that got wet in the basement where my tank is after a water valve broke a few days ago. I've lost almost all of my Favias and Acans, ALL of my Yumas, about 20 Fla Rics and probably a dozen Zoa colonies/frags.