Maybe a pine shaving sliver? I also just kept mine on paper towels.The ONE thing that I am seeing is that she is on shavings.
if she ate some that would explain several things, small poops, neck scratching, extra stretching maneuvers to name a few.
One other thing that would make her sleepy, and the small poops would be if she is having trouble with the chick feed size.
I keep chicks under a week old on paper towels and I crush the starter to make it much smaller.
Just my thoughts.