Oh, probably Cecal worms then if they are tiny.
Levamisole should take care of those.
If they have river sand then there may be suitable grit in that. Usually insoluble grit (granite or flint) is sold at feed stores or is here in the US. I'm not sure if that's a thing in other parts of the world.
You mention that she had been broody, but has come back into lay. Broody hens have a special kind of overwhelming poop that is just disgusting as you know. It's like did you really do that?!!
Hopefully she will come round if she's been broody, I'd see deworming helps. The food not being processed/ground up if what I see as a concern, but if she does have worms then it's possible once they are taken care of, then the issue may be resolved.