Pullet with yellow poop

[apryl29]

I have a delaware pullet that's about 10 months old. Yesterday I noticed that her normally white feathers under her cloaca looked stained yellow. I checked her out and everything back there looks normal other than the staining to her feathers. Yesterday I let all the birds out to range and she was milling about the same as all the others, eating grass and digging for bugs. She's walking normal, running & flapping her wings. The only thing 'odd' that I noticed is that she did puff up her feathers a big more than the others. I'm in Ohio and we've had a bit of a warm spell the past few days, it was later in the evening as it was getting dark that I saw her puffing up. She ran and jumped into the coop with all the others when they went in and pecked around the floor. This morning I found a pile of watery yellow poop that I can only assume came from her. I had seen a couple splatters in the snow over the weekend, but it was dark and I couldn't 100% tell what it was. When I opened the pop door she ran outside with everyone else.
Any idea what could be causing it, or if I should be concerned?
This particular bird had seemed to lose quite a bit of weight earlier in the winter, but in the last few weeks has been gaining weight again. She's also currently molting, not sure how severe as it just started this weekend and I'm seeing white feathers about and have noticed feathers falling out and some pin feathers on her while I was checking her out yesterday. I'm not sure which eggs she lays so I cannot say for sure when she last laid.
In the poop there is a bit of clear liquid that appeared to be like egg whites.

 

[Smuvers Farm]

Are you certain it is just poop and not a shell less egg?

 

[staceyj]

Based on the skinny diameter of the dark poop, I'd be inclined to glove up and feel around in there a bit.

 

[apryl29]

That's what I thought about the stuff before, but the yellow stuff looked more like the consistency and color of mustard.

 

[apryl29]

Unfortunately I already scooped it up this morning, but I'm heading over there during my lunch to close their window as it's supposed to start snowing here soon. I'll see if I can find any new deposits. What would I be looking for?

 

[Smuvers Farm]

Calling in @WVduckchick @casportpony @azygous @Pyxis

 

[21hens-incharge]

Following to learn. Sorry I cannot help.

 

[apryl29]

Following to learn. Sorry I cannot help.

Don't be sorry! Always better to learn something before you need it.

 

[CSAchook]

Following to learn. Sorry I cannot help.

X2 And to send good vibes

 

[apryl29]

She was sitting in the nesting box when I got there, but the egg in the box wasn't warm, so it likely wasn't hers. While I was there she pooped again. (photo below). This time more solid. It was kind of like the yellow stuff was on the outside of her actual poop. I dug through it using a stick b/c I didn't have gloves & I didn't see anything that looked unusual.. a little of what looked like intestinal shedding, but not a lot & what I did see was inside the darker color poop, not in the yellow stuff. Pretty much just a normal poop w/ yellow on the outside. (the thing sticking out of the bottom is a piece of straw.) I'll check again later.