I have a red sex link that didn't make the little hop into the coop last night. She's sitting on the ground and not really getting around. Not seeing any noticeable signs of injury, I checked her vent and cleaned it. It appears swollen and there seems to be some discharge. I've heard egg yolk peritonitis is common with these. Do you think this is what it is, and what should I do? I've had a couple die this way and it was grisly.