Yea we need to know what they are feeding, how they are feeding, and when they are feeding to help you out more. For example if they are just being offered frozen thawed and easy fix is trying live until he gets his appetite. Of course this being Petco I thin feeding live is against their policy. If they are feeding frozen thawed then they may not be warming the mouse or rat to proper temperatures. Try getting some of the bedding out of a rat cage or mouse cage and rubbing it on the feeder mouse/rat so this way the feeder picks up a fresh sent for the snake. You could always try the paper bag method where you the rat pup or small mouse (frozen thawed or pre killed preferably) in a paper bag with the snake for a fey hours and see if he eats. Sometimes providing more security (hides) in an all glass enclosure well help in insecure snakes with appetite issues. All these suggestions could be applied over time, but for now with the current condition the snake is in you should really try force feeding him a small meal. Good luck dude hoe it works out for the little guy!