I see you asked the same question over at Repticzone, and I like this answer better (although the suggestions over there have merit).
Your snake might also be getting ready to shed; I don't "do amels" so I'm not familiar with the color changes that preclude it, but only one of my snakes will eat while in shed, and with couple of them, the first indication I receive is when they refuse a meal.
I see you bought your snake at Petco, and you were certain you were going to get blasted for this, but having made your choice (and some don't have any other source of herps), it's doubtless time to move on . . . Your cage is really large; I have a year-and-a-half old corn I raised from a clutch I hatched that I still keep in a ten gallon tank (yeah, something larger is in the works); cage size probably figures in your decision to feed outside the cage, something I generally advocate (I do have a Nelson's milk that will gently take a pinky from my hands in his cage, but he's full grown and that only happens when one of the other smaller ones refuses something and I don't want to waste it). So give the little guy a break as suggested . . .
The only other thing I'll add is a plug for the time-honored wisdom of making sure a snake is eating before purchasing it (particularly with hatchlings); this saves a lot of worry and heartache . . .