Cayuga Duck has rash on bill

[Meganyoung]

My 4 year old Cayuga Duck has recently developed a rash on her bill. It’s very bumpy and the top of her bill looks dry. She has had it for about six months now, but it has gotten worse. I’m not sure what to do, and can’t seem to find anyone else with the same problem. Does anyone know what it is and how to help her?

 

[Eggcessive]

I am not very good with ducks, but others such as @Miss Lydia can be helpful. Can you tell us more about how you are keeping your ducks? Is there any mold in the area? Do they have a source of water to rinse their beaks?