I did that and he is hanging without move, only moving his tongue. I touched him in other place and he quickly moved, earlier in the morning he didn't so I think it's a good sign.
As you wrote about the lethargy I also put him today with the box in other place than usually and he has higher temperature there.

About the scale rot, it looks like this



I asked people who hold gathers in Poland and they all told that fungus is common in thamnophis and it looks like this (I sent them bigger picture, i know that you can't see on this much), my vet told the same thing so I thought they were right. He got better mostly after he shed.

Thank you for your suggestions and I hope that my snake will make it and will be healthy