My leghorns started laying eggs rather early (18-19 weeks) but have been laying for the past month or so. Nice large eggs, no weird shells. One of my girls didn't lay for a few days and now she's just standing around puffed up. I thought it was possibly a sour crop (it was rather enlarged but soft, like a gas bubble), so I massaged it and gave her a little olive oil. She was still eating quite well, although now she's just nibbling. She's drinking water normally. Gas bubble appears gone now. No bad breath (whatever that means for a chicken!!) I then thought maybe cocci - so have been giving her corid the last few days. Her poop is greenish, no blood. She had a bout with a similar illness when she was much younger (green poop, puffed up, standing around) but even though she was better after corid, it may have just been a coincidence. I checked for mites, saw no evidence. No evidence of feather pecking, etc. I do have Eprinex if needed although I don't SEE any worms. She does have a whitish goop (just a bit) coming from her vent, but doesn't look very 'egg-like'. Her abdomen does not appear swollen. Her vent is a bit pale, no prolapse. Yesterday I saw her just standing in the nest box. The other chickens appear fine - I've been keeping her separated while I am at work (just in case) and letting her roost with her broodermates at night. No eggs, obviously. Comb is still red and flopped over her face. No scaly legs, no bumblefoot. She does walk really slowly, probably due to weakness. I've given her poly-vi-sol (no iron). I have not yet checked inside her vent, but there is no obvious signs of straining. No sneezing, eyes are clear. Any thoughts? I thought she was getting better two days ago (was running around and eating as usual) but now it seems she has relapsed. Could this be an internal laying problem since there are no eggs and she started early? I have on hand tylan injectable, eprinex, sulmet and tetracycline.