HCA: Hermit Crab Association

I do believe he is surface molting. Today however I saw mites on him and he's not moving at all and stinks. Would this be a sign that he's probably gone.

Food is General pet store food. He has the ability to bury completely on the soil.that was something we made sure of. The soil and sand are side by side. No exposure to any chemicals or anything. The sand is crab safe sand Zoomed salt water Other than store food, we have a safe list of veggies that ...

Everything that I know for answers are in my initial response.I don't see how this could be post purchase since she has had it almost 2yrs.
Is there anything else this could be.

my daughter was doing a hermit crab check today and noticed that her large hermit crab was not moving very much. she did isolate him in a small tank. she doesnt think that he has been eating or getting in the water very much. he appears to be coming out of his shell. he is not moving very much at al...