HELP - - Sick Emerald Crab

[fortheloveofcrabs]

HELP!
I have an Emerald Crab (Bubbles is his name) and I have had him for a couple of months now and I have noticed that over the past little while he has stopped eating. The water params have not changed and nothing has been added. He has lost almost all of his green color and has turned almost completely white. I picked the little guy tonight just to get a better look at him and he was very week and sickly. I put him on a rock with some bubble algae in hopes that he would eat. He is just laying there on the rock. Any ideas what is wrong with the little guy? What can I do? Please HELP!!

Thank you.

-Distressed