I think your hen could be suffering from egg yolk peritonitis from your description. A vet could diagnose it, but most of us don't know for sure until the hen dies and we do a necropsy. Antibiotics such as enrofloxacin (available online,) Gallimycin (erythromycin) or procaine penicillin G injections may help with infection and extend her life, but she may continue to be ill from this later on. Liver failure and ascites (fluid collecting in the abdomen) can be common with EYP. Here is a link for enrofloxacin and some info to read on EYP:I need help now my White Leghorn seems like she's egg bound and has been laying chalice eggs just with the insides of the eggs on the ground and she drops them anywhere. She's gone to lay but she hasn't made anything in the last few weeks except the one day she drop some liquid that would be the inside of the egg on the ground. She can still push out like clear fluid and yellow fluid of what would be inside the egg out of her vent but she's very full and on the side of lethargic not moving around much. Please advise
https://www.backyardchickens.com/t/959119/baytril-enrofloxacin-sources
http://www.chickenvet.co.uk/health-and-common-diseases/egg-laying-issues/index.aspx
http://scoopfromthecoop.nutrenaworld.com/tag/laying-issues/
https://www.backyardchickens.com/t/526089/egg-yolk-peritonitis