Jack's own clothes are rather worse for wear-- between the fight, the transformation, and whatever happened when he changed back to his (mostly) human form, his formerly fairly expensive shirt is in tatters and his trousers definitely feel like they're likely to slide off his hips if he stands up.

He lets John catch his shoulder, looking up with a dazed confusion, until he recognizes the person in front of him-- and the state he's in--

"Oh no. Oh John. I'm sorry, I'm-- are you all right? You look--" Not actually like he got in a fight with a werewolf. Nothing seems to be... actively bleeding? But he looks like he's had a hard night, even so. If he's in the same vicinity as a werewolf, there might have been violence, and it's his fault. He didn't warn him.