Is this just an ear infection?

[EdwinLegn]

 

[azygous]

A photo is only two dimensional, although it's a very good one. You need to flesh it out with some background information.

General climate at your location
Recent environmental conditions/ temps.
Age of this bird
Discharge from ear?
Has that lobe been treated with anything?
When did you first notice this?
What did it look like when you first noticed it?
General behavior/changes?
How many in the flock, average age, any other adult roosters? Do they fight?
Has there been any sickness or deaths recently in the flock?

 

[Eggcessive]

Seeing the bluish swelling makes me wonder if there might have been a tick bite. Those can inject a blood thinner, and cause bleeding in the tissue. There have been a few of those reported here on BYC in the past. If that sounds like a possibility, I would give 1/2 tablet of benadryl only once, and look for any ticks. Hopefully the swelling will go down.

An ear infection or a tumor could also be possibilities. Is there any head shaking or other signs of a respiratory or ear infection? You can examine the ear canal with a QTip for ear mites or gunk. Hope you figure it out.