Check the temperature and the humidity. Provide additional hides, including a humid hide. Cover 3 out of 4 sides of the enclosure. The temperature may be off, the humidity may be off, or the snake may be feeling insecure and exposed. Or it might be something else, but they don't burrow for fun.

As far as substrates go, newspaper is in my opinion more practical than paper towels and carpet starts to smell. As far as carefresh (and paper pellets) goes, I'm never going back to using that crap.