Large squishy crop

[Mrs. Light Sussex]

I've got a barnevelder pullet 18-20 weeks old, several days ago I noticed a lump extending forward in the crop area. 02:30 AM I checked the crop, it is large (slightly larger than expected at the end of a day, just a reminder we're talking approx. 8 hours after shuteye) and squishy kind of like a balloon.
She eats layer pellets, veggie scraps and free ranges. Grit is available at all times.
I opened her beak, there is no foul smell coming out.
Is it a sour crop? What should I do?

 

[Eggcessive]

It could be just a slow crop due to another problem, so I would massage it several times a day, and stop solid food for a day or so. Give her a mixture of egg and plain yogurt, and lots of clean water tomorrow. If the crop has gone down some by the next morning, you can slowly give some wet feed, more yogurt, and keep massaging. Look for TwoCrows good article on "impacted and sour crop prevention and treatment."