White lump on chicken head

[Bkydchickens]

I don't know if it helps, she's about 4 years old & vaccinated. No one else has it. She's acting normal. We are in a drought, over 100 degrees. She free ranges, in a large run & coop at night with hemp mulch. Thanks in advance for your help!

 

[Wyorp Rock]

Could be ear canker.
See the link below for more info and treatment.

https://www.backyardchickens.com/threads/both-ears-have-infection.1579065/#post-26826134