I personally despise crushed walnut shells and think it should be banned. My bad experience stems from a bearded dragon that was kept on reptile carpet most of it's life and then sold to a pet store, which in turn put the beardie in a cage with crushed walnut shell bedding.
I don't know if there was something on the shells that tasted good to the beardie or if it's inquisitiveness caused it to constantly test the substrate. Either way it consumed a large amount of it before I bought it from the pet store. It died a horrible death from impaction, even after $200 in vet bills. The particles are too large & rough and doesn't break down, causing blockage between the stomach & the intestines.
I'm well aware of the differences between a lizard and a snake, I also noticed you feed your snake in a different container, but the potential is too great just for our personal satisfaction of having a good looking substrate versus a safe & effective one.
"The weird though is he has been kept on the walnut shells for about a year. So why is it now bothering him?"
Burrowing in the crushed walnut shells the snake has been fortunate up to this point. The odds could've finally caught up with it and it could've had a piece of shell get lodged in it's nostril.
I've always said that if you wouldn't feed an animal on the substrate within it's cage then you shouldn't be using that substrate. It's just a matter of time.
I hope your snake turns out just fine.
Warning!
Below is a graphic photo of the bearded dragon I mentioned earlier. You can see the crushed walnut shells mixed in with crickets in it's stomach. It really was pitiful.
Have a good one!
HH

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Due to political correctness run amuck,
this ol' hillbilly is now referred to as an:
Appalachian American

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