If the crop doesn't go down it could be impacted. I have one chick that got impacted. I was able to resolve the impaction but not before her crop stretched and became a bit pendulous. It's slowly decreasing in size and toning up. There are lots of threads on crop impaction if you think it's more than just a normal full crop. I think if I was more experienced and able to diagnose the problem sooner, my chicks crop wouldn't have gotten so stretched out.