three year old Isa Brown vent area stays nasty.

[Wyorp Rock]

Is her crop emptying completely overnight?

She may have a two-fold problem going on. Vent Gleet and reproductive problems, since you noticed she seemed to have some swelling in the abdomen.
Treat the Vent Gleet the best you can and monitor the swelling, that is about all you can do. Try to encourage her to eat her normal feed.

Does she look like any of the photos below or possibly a combination?

Swelling/Bloat/Fluid of the abdomen

Photo reference

Vent Gleet

Photo reference

 

[bucky52]

yes and no.She is very red like the picture.She had a lot more poo stuck to her feathers.