Why is my budgie changing color?

[GryphonHound]

A few days ago this yellow mark on his forehead appeared, at first I just thought that it was a lettuce stain but as the days went on it started getting bigger even though he didn't have access to any thing that would stain his feathers. (Dont mind the bad quality picture, he kept on trying to jump on my phone and this was the only calm picture I could get)

 

[Rico_Tiel]

Does he have any yellow toys? That could very easily be a culprit!

 

[DonnaBudgie]

A few days ago this yellow mark on his forehead appeared, at first I just thought that it was a lettuce stain but as the days went on it started getting bigger even though he didn't have access to any thing that would stain his feathers. (Dont mind the bad quality picture, he kept on trying to jump on my phone and this was the only calm picture I could get)
View attachment 53108

He's beautiful, and looks like friendly little guy, too! It looks like a stain maybe from accidentally getting some wet poop on his face and smeared it trying to wipe it off.