Houdan death

[Hollyb-c]

I bought Hannah last year with another young chicken, a top hat. They both had a bad infestation of tapeworm and mites. I got them both well (clean fecals) and put them with my 4 chickens. Last week I noticed Hannah had sort of a wet vent and saw what I thought was eggs on vent feathers. The top hat had some eggs under wings. The coop was cleaned and sprayed with poultry protector. All birds were bathed in Adams flea and tic shampoo. I took great care to blow dry everyone. This was 4 days ago. Yesterday I noticed Hanna was not herself, rather lethargic. She as eating so I just kept an eye on her. I checked on her in the coop last night and she was on a perch by herself, not with the other chickens. I found her dead this morning. It is Easter Sunday so necropsy is not possible. I am so sad. Any ideas about reason she died? I was reading about egg bound symptoms but she did not seem to sit funny. She did look a little hunched, but not much. My other chickens are fine. Thanks for any comments.