The crop should be normally empty in the morning, and gradually fill up with food and water by bedtime in the evening. If it is full in the morning, tell us if it is soft and mushy or hard, or dough-like. Crop problems can be from different causes. Coccidiosis may sometimes cause a puffy or slow...
Since she is 3 months, if she seems like she might have coccidiosis, with symptoms of lethargy, runny poops, not eating, and standing around puffed up or hunched, I would start some Corid (amprollium,) from the feed store. Dosage is 2 tsp per gallon of water with the liquid, or use 1.5 tsp per...
Is there any food in her crop tonight? How does it feel—empty and flat, full, firm, doughy or squishy? Recheck it again in the morning before she has any food or water. Did you get other birds from the seller? Do they seem okay? How did it seem like they were kept previously? It is pretty good...