Has she been able to pass stool? She should be kept somewhere away from the other birds for observation. I'd say she probably has impacted crop but she could also be blocked up from worms. There are many threads regarding these conditions. People have massaged the crops with great success and the birds have gotten better. It's recommended that if you don't have a regular worming regimen that you should send in a fecal test to see if internal parasites could be a problem. Withhold food from your bird until she's able to pass stools and clear her crop but keep providing her with plenty of water.
If you notice a sour smell coming from her beak it could be sour crop which can be fatal. Please give as much information as you can so people will be able to assist you with your bird such as worming schedule, age, diet, if there is a sour smell coming from her beak and if she has been able to pass stools. I hope she recovers soon.
