It's about the size of a golfball, but not as deep and dark and scabby with raised edges...on the back of his head/neck... Not really visible until you push his feathers back...he's americauna, so he's got quite a mane.
Now that we've cleaned it with saline solution and pushed the feathers back it's become clear that it's a hard mass with a scabbed surface. It's almost like you could just cut it off... It seems like it's moveable... We cleaned it and put neosporine on it and are keeping him isolated.
It's really more on the back side of his neck maybe an inch away from his ear. It feels like a flattened golf ball under his skin or like a thick hard pancake with a scab. I also see what looks to be a tiny one coming up next to it. It is about the size of a Lima bean