Problem spotted! Sand or shavings consumption kills a lot of chooks. That, right there, is why she's in this state...
She needs fiber, as soon as possible, to shift that sand before it kills her. There's a strong chance her crop and/or stomach and/or bowels are full of sand she is struggling...
Are you absolutely, 100%, sure that these are her poops? Not some other animal? I mean, you say you watched her, but yikes... I can't imagine what 6-week old chook has the internal capacity to do 6 inch poops, many 12-month-old chooks do not have that physical capacity! Maybe she's not actually...
Ah, lol, I did misread that! 6 weeks... Yikes. Eh, was past my bedtime hours ago.
How big are the poops? More than twice the usual size? A slowed or 'sluggish' digestive system can cause that.
Best wishes.
Sounds like she was or is broody. They can do egg-sized poops when in that state. If her breast is bare, which you won't see but have to touch her to find out, then she's hormonally in that state, though whether or not her instincts are sufficient for her to even react to it is another matter...