He looks very VERY thin to me.. You see that triangular shape of his body? It should be round and plump. The skin wrinkles could be dehydration, but I think it is because he is so thin.

His head shape is a little strange, but if he eats just fine I don't see a problem. A vet could do an x-ray, but there is nothing you can do about a deformity like that. So I wouldn't see the point.

I know you said you were using a thermostat, but the nearly 2 week long pink belly leads me to believe it is a burn. Could you tell us where the thermostat probe is placed and where your probe for the thermometer is placed? These two small things can have a big impact on the temp the snake actually feels.