The face looks like it is peeling. She could be scratching it. Could you get a more picture of the inside of the beak? Canker, which looks similar to the wet form of fowl pox, but has a bad odor. Pox is a virus caused by mosquitoes while canker is a protozoan infection carried by pigeons and other wild birds. Canker can be treated with anti protozoan antibiotics such as metronidazole, while wet fowl pox has no treatment. It lasts about a month. Have you seen any lice or mites on the skin? Has she been pecked or have you see her pecked? Has she been dust bathing?