Sore chin

Hoping you might be able to shed some light on this for me?

Thomas for the past few months has had hair loss on his chin, but today I've noticed it looks sore and shiny
I thought it was due to old age but because it is suddenly worse I'm worried.
He is behaving no differently and is still shouting at me to be fed so he doesn't seem to be bothered by it.

Does anyone know how I might be able to treat this at home?

Nobody here can diagnose from a picture - especially as we're not vets!

It sounds like it's worsening quite quickly, which is even more of an alarm bell to me. Please get him to the vets to get it checked.