An impacted crop will typically feel large and quite hard, and most of all it will not empty over the course of the day. Generally, a bird's crop should be empty when you let it out in the morning, full after it has eaten for the first time of the day, and then over the day it will shrink some, until the bird fills it's crop again just before night falls. If the bird's crop is not emptying, that's impacted crop. You should separate the bird and remove all food. For now, you can give the bird some vegetable oil and water with baking soda, and check the crop regularly to see if the impaction has begun to pass.
