I agree with Becky on the E. ColiSounds a lot like internal canker (also called wet canker). But the other questions are important to determine this. Birds with wet canker will often have a penguin posture, standing upright, with the tail down, and the crop/neck often looks 'swollen'.
Another thing that smells is e coli, but I'm not sure if that would cause clear droppings or not. It can disrupt the digestive system pretty badly, so I suppose it's possible.