how are you offering him his food?
do you feed him in his bin?
do you transfer him to another bin for feeding?
do you feed at night?
is there any form of distraction in the room when you feed him?
was he a strong feeder to begin with before he went off food?
what are your temps/humidity?
how quickly did he drop his weight or has that been gradual?
can you show a pic of his set up?
has he been out hunting for food?
oh and what size prey are you offering?
sorry to bombard you with so many questions but these are all things that are relevant when it comes to a snake getting stressed on feeding day?
john