Is my axolotl getting sick?

Today while I was feeling my axoltols I noticed my one juvenile melanoid has this white patch near its back legs. Around his gills have always been absent of colour almost , like white but more opaque ... but I've never noticed this on his body before, is that just a normal colouration of his?
Also... when I was looking at his back, parts of it look also like a different texture. It looks almost like it's dry or something.
What could be the cause of this ?
I recently did a huge tank change , pulled up and rearranged alot of my live aquarium plants . I think in doing so I kicked up alot of nitrates so my levels have been high the past 2 days. I've done a water change already and it looks like my guy still has a great appetite other then the skin change.
I'm a new axi owner so I'm quick to jump to him being sick!
I would really appreciate any thoughts or comments you have !

Hmmm it kind of looks a little like his slime coat is shedding. Have you tested for ammonia and nitrite? Is the tank cycled? Also, what is the temperature?

Skudo09 said:

Hmmm it kind of looks a little like his slime coat is shedding. Have you tested for ammonia and nitrite? Is the tank cycled? Also, what is the temperature?

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Ammonia is 0 , but my nitrite is pretty high at the moment .... I changed around my tank 3 days ago now (moved around alot of the established plants) so I think I messed up and released alot of the nitrates Into the water from the substrate, I've been doing water changes to get on it. But the tanks been cycled for 2 months now . Going on 3 months.
And the temperature is 20

So what should I do to counteract this? :s

If you have nitrite in the water, the tank is not cycled. What are the exact readings? Nitrite is toxic to axolotls and is likely the cause of the slime coat shedding. You are best off placing your axolotl in a tub of fresh, cool, dechlorinated water and change 100% of the water in the tub daily whilst you work to rectify the water quality issues in the tank. Clean, cool water will help the healing process. You could also offer a black tea bath to soothe the skin.