I need to know specific water parameters, especially specific gravity, pH, nitrates, and alkalinity. Any recent water changes, or changes to the tank (eg temp spike?).
FWIW, IMO the tank is marginal for keeping one of these long term, and it is at the time frame now when starvation would be a possible problem. Most will not take to spot feeding....could be a potential problem in this case. They effectively start to "melt" and arms fall off.