Since your pullet just laid her first egg, could it be that your entire problem might be an impacted crop? Once, one of my pullets had some watery greenish poop, that looked just like that. I think I lucked out because it went away pretty soon & I didn't have to deal with it. I now think she had an impacted crop & that it cleared on its own. If something, like a long strand of grass, is blocking the crop to the point that only some watery poop can make it through, I would think this could cause the problem. I understand that it takes 24 to 27 hours for a chicken to produce another egg, so are you sure there actually is another egg at this point or could it be swelling from the ordeal with the egg she laid?
There are a lot of videos online, showing how to clear an impacted crop. Here is a link to one: https://www.youtube.com/watch?v=sAX7VdX8r-s