I'm not quiet sure what that is ... Any chance of it just being a odd little deformity? You said it's been there a while at least 2-4 sheds right ? I personally cannot see any scars that would make me believe it was maybe a rodent bite or precious injury to the area... Is it hard like a abscess ? Still pretty weird area to get some kind of abscess... I'm stumped to be honest sorry I'm not much help I have personally never seen a bump like that near the eye. I guess maybe a vet trip ... Just to confirm it isn't some random infection for what ever reason. Just really odd spot. Sorry I couldn't of been more helpful. Keep us posted what you find.