Does her abdomen feel bloated, below the vent between the legs? Her stance suggests reproductive problem. It's not uncommon, particularly in birds over the age of two, and in breeds that were bred to lay lots of eggs, which she is. It could be an infection like EYP or salpingitis, or a cancer. If the abdomen is bloated, either very firm, or water balloon like, then the the prognosis is usually poor. You may be able to keep her comfortable for a while, but it may not be fixable. Green droppings can be from not eating (bile), or can be an indication of infection or cancer. How is her body condition, is her keel bone well muscled, or is the keel bone very prominent? If her abdomen is not bloated, then you could also try a round of antibiotics, like amoxicillin, to see if it helps. If there is bloat you can still try antibiotics, but they may not really help. Often for reproductive problems like salpingitis, enrofloxacin is used (not approved for poultry, but some vets will give for pet birds). If it's a cancer, then there really isn't a treatment.
Since she is passing droppings, it's less likely that this is egg binding. I've seen birds that are egg bound high enough for droppings to still pass, but most often the egg blocks the passage of droppings.