I don't feed them anything but their regular feed and plain water until I have a better idea of what might be wrong after a couple days of the isolation I outlined above.
Not good. The scratch dilutes the already minimal nutrition of the layer feed.
What exact layer feed are you using...and what ratio do you mix the scratch in??
Is the "grit" you also(?) mix in Oyster Shell or Granite Grit?
What kind of grains?
Layer feed is supposed to be the sole diet.
This is what I do when I have a bird that is acting 'off'....
I isolate bird in a wire cage within the coop for a day or two....so I can closely monitor:
-their intake of food and water,
-crop function(checking at night and in...