Don't worry just yet, How old is your snake? If it is a hatchling, It's quite normal for them to be fussy and refuse to eat. When he does refuse, don't try again every day, Try every 5 or so, Otherwise he may get conditioned to refusing and we don't want that.
I'm not so sure why he's pooing more, Someone else can handle that one, But obviously its going to look different since he hasn't eaten and has nothing really to poo.