Yeah, you might want to take the eel, chromis, sand and everything out and just start over. Possibly there is something inside one of your rocks. I'm guessing it's something bacterial. I'm gonna do some reading tonite after work and I'll get back to you tomorrow to see what you came up with.
Possibly brought in by your PJ. You said a while back that you run a UV correct??? If you don't you may want to consider getting one. I know I thought they were expensive, but when I thought about losing $700 worth of fish , $150 didn't sound too bad. You might want to write in to AFM and ask Scott Michael what he thinks.
I'm assuming that you checked both fish and the PJ for scars/injuries to see if they had been injured or anything like that.
Once again, sorry man. Those coral cats are great for the aquarium too. Wish all works out for you.
-tony