I went into the coop this morning to find her in a puddle of yoke-like substance. Looked as if she had slept in it all night. Also found she had layed an egg (unbroken). When I first let her out she acted perfectly fine. Drank some water and walked around. Only a few minutes later she started acting listless and ill. She has what appears to be egg yoke leaking out of her vent. She can hardly walk. She keeps nodding off to sleep. I've washed her off and cleaned her vent. Her vent is still leaking. She's swollen back there. She'll drink some water, but won't eat. She was perfectly fine yesterday. She's a banty around three years old. She's never really layed eggs regularly. Lately it's been once in a blue moon. Never had trouble with her before. I've isolated her from the other chickens for now. Please help. I'm very worried.