I'm so sorry to hear about Thelma I lost my Daisy in a similar way in January, It's heart breaking because she left her sister behind.
I know it is probably difficult to think about now, but you need to get Louie a new friend asap. When Daisy died, her sister went downhill very rapidly - she...
If she has been laying, she might have made a nest in a very hard to find place and could be sitting on eggs - I really suggest you get a search party out, take some treats and search the whole area.