Sure bought grit is great I'm just cheap 😁 I would think if they can eat sand and grit a small amount of wood shouldn't stand a chance inside the crop especially if they got grit in their crop.
Shavings are dustier and mine love to dust bathe in them especially the tiny flake stuff. I like them cause I can stir it and don't have to clean ever day 😁 I imagine it could be itchy and growing feathers must be itchy too! I really hope it isn't bugs!! Please be itchy dust in feathers not bugs!