I'm not,.....an expert with my carpet, but l really don't think it's the nitrate or phosphate, as there not high enough to cause a serious issue.
I had mine In a tank with 25-30ppm for 2 months, with no ill affects. I was freaking out when mine would be in odd shape, thinking something was wrong and it's dying but the next day it looked fine. After several months I got used to it changing shape's, so maybe yours is doing the same ?
The question,..... if yours is about his mouth, is it really turned inside out ?
Have you fed it or has it ate something it shouldn't have ?
One of my branching SPS's fell onto my Carpet, but I saw it right away, so with some patience I was able to remove it without doing damage to the carpet.
I've seen some that are always spread out and never move, but others that change shape and move. Mine has not moved from the day I placed it where I wanted it.
Keep everything the same, like lighting and the water movement.
So, keep an eye on his mouth and maybe he's just being a carpet.