Illness/Sickness: Spotted salamander

[JustRuby]

Okay so I've had my salamanders and toads for years without bother until now. My spotted sal has suddenly become really lethargic and he's curled around and quite stiff. Like I put him in a quarantine area til I figure this out and he's seen the vet and when I lifted him he was stiff. I would have thought he was dead if it weren't for his blinking and throat moving. He does move his head from time to time and he kind of wriggled once making me think he was stuck in his shed but it doesn't look like it.

Only difference I can think of is I added more coir fibre to his enclosure to deepen it more as he was hiding away more with it being colder so I figured he'd want to burrow. I normally use plantation soil coir and topsoil but this time I only used zoomed coir. Few days later he became ill. I had a closer look and I can see what look like salt granules in the substrate? Or I assume something to benefit live plants...id never used this one before
If he'd decided to hibernate would he go stiff?
Any ideas or suggestions?
Temperature sticks around 16-18C

 

[Sith the turtle]

What are his temperatures? What type of soil are you using? What is his setup? What does he look like? If you can answer these questions, we can help you. I take it your salamander is an Ambystoma maculatum right? If so, they have very similar care to the tiger salamander

EDIT: I see you already listed his temperatures

 

[Bellabelloo]

Could you provide a photo of him please?

What have you been feeding him?

My maculatum are still very active at 5 C, so 'hibernating' is unlikely. In case there is something in the soil, I would remove him immediately and maybe put him on damp kitchen paper. Keep the container covered. What did the vet suggest was wrong?