Phal with crown rot... HELP!!!

[QHMaverick]

I have several phals, almost all of which are in potted bark. Two of them are not, and I had plans to remedy this situation today when I made a very sad discovery. My largest phal (which is in peat moss) is not doing well. The entire crown of the plant came off this afternoon.... leaving no leaves. Over the last few weeks it dropped several leaves, which I thought was because it got a little too much light when I moved them to a different location. Now I'm worried it is dying. What am I dealing with here? How do I attempt to save this beautiful plant? I have been keeping phals for 3 years with really no major issues. It figures the one that is dying cost $$$! I'm willing to do whatever it takes to save it, just not sure where to start and what to do.