She's roosted with the others tonight, so I'll pull her out in the morning. She's acted fine all day. The swelling is really a baseball sized boggy sack. It's way posterior to where the crop is, but it sort of has that same kind of feel as sour crop. It's definitely warm and red. Looking at an anatomy chart it seems that it's where the gut should be, but there is no evidence of constipation. A bound egg should be more toward the top, I'd guess.
Absent any other ideas I thought I'd do a warm bath treatment. If I can get to a store to get some gloves I guess I'll try to see if this sac is connected to the vent. The vent looks fine. I can give her some oil orally, also. So I'll keep her inside and see what happens. I can't find anything anywhere on the internet that describes this sort of symptom.
Please let me know if anyone has any other suggestions. (Can't afford vet).