Our red sex link layer, 20 weeks old and laying eggs steadily, suddenly has a very large crop, completely full, the size of my husband's fist, and very tight. He can feel the gravel inside when it is touched. We're concerned it's not normal and that she may be in trouble, although she's still eating like crazy and seems to be in normal spirits. DH did a massage to loosen it, and it helped a little bit but not enough to make a real difference. Her breast is really sticking out. What is this, is it cause for alarm, and if so what do we do about it?