Her posture with the tail down and more upright condition looks very much like she has a reproductive problem to me. I would also check inside the vent with one finger inserted up to 2 inches for a stuck egg, where it should normally feel soft. The green droppings look like she is not eating much. Try adding water to her chicken feed to make a mush, offer cooked egg, tuna, or liver just to make it tasty, and to get her eating.
Chickens with reproductive disorders make suffer poor digestion, crop disorders due to swelling or fluid in the lower abdomen.
Chickens with reproductive disorders make suffer poor digestion, crop disorders due to swelling or fluid in the lower abdomen.