These are swamp snakes. IMO the cage is too dry, and the snake is waiting out the dry season. Try putting water in the cage until it covers the entire floor about ~1/8 inch (~3 mm) deep. A breeder I know uses newspaper sheets as substrate in a plastic sweater box (approximately 16x8x6 inches). He adds approximately that much water to the box and puts in a hiding box and a water bowl. His babies feed on baby rats that have just reached the fuzzy stage. I'd think a hopper mouse would work too. And I'd wait a week after adding water before feeding again.
Good luck.