Water Belly and Swollen Eye

[Wild--Star]

Is there /anything/ that can be done about water belly? I believe my last hen has it and she has suddenly become very lethargic. I also noticed she is very skinny. She had a case of red mites that I am treating with Pesterene also.
On top of this, one of her eyes is swollen. It can open fully but it's leaking clear liquid and the whole red ring around her eye is swollen. I have no idea what's wrong or what to do.
She's getting worse by the day. Today she didn't even want to leave her coop. When I spoke to her she shook her head. And she is mouth breathing a lot like she is hot. She does feel very warm underneath.
I have been putting Oximav B (respiratory antibiotics) in her water for about 3 days and she has not responded...

My hen is 5 years old, she is a pekin frizzle and she's a sweet little thing. She lost her flock mate last month but she seemed her usual happy self. She actually started to crow in the morning for a couple of days, before she got noticeably sick, and I found that her eggs had a perfectly yolk but the whites were thin and stayed quite transparent even when cooked. I've been scrambling her eggs and feeding them back to her. She was eating really well and was scratching around normal until yesterday when she seemed a bit lathargic and today wouldn't come out of her nesting box at all and didn't want food. She pecked at only a few seeds I offered her (which usually shs loves) but she ate the egg thankfully and she was drinking a bit of her antibiotic water. Her clucking was very weak today and I'm so worried. This happened so fast. She seemed fine!
I feel guilty, I was so worried about my other sick chicken before she passed that I never noticed anything was wrong with Daisy.

 

[Wyorp Rock]

The eye swelling may be due to the mites. I see some around her eye in the photo.
Does she have any lesions or yellow/white pasty material inside her beak?

Ascites (Water Belly) is a symptom. Hard to know the cause, but in laying hens reproductive disorders like EYP, cancer, Salpingitis, etc. can be common. Ascites can accompany these disorders. There's no cure, but sometimes for a short period of time fluid can be drained to offer comfort measures/supportive care to the hen. Sadly, whatever condition is causing the fluid will eventually overtake the hen.

The mites need to be addressed immediately, they will cause a hen to go downhill on their own. See that she's eating and drinking, the antibiotics may help with inflammation.