Blood/burn on balls!

[annachristina_piggies]

Hello! My big pig Percy has recently experienced some sort of injury to his balls. I thought it was fresh blood but upon close inspection, it’s almost like a carpet burn. The blood won’t wipe with a damp cloth, the skin looks tight/sore where there is redness. No idea what this could be, but he’s pretty active and behaving normally. He’s booked in to the vets early next week anyway for a check up on his respiratory infection (which he’s recovered from and just finishing antibiotics). He lives in a large indoor fleece set up, changed regularly, with a young new friend after his cage mate recently passed.
Anyone seen anything like this before?
Sorry for the graphic photos!

 

[Wheekallweek]

Aw poor little fella, I have no idea but perhaps a friction burn? Either way hope the vet can clear it up for you!