Our Scratch boy is fine. Thanks everyone for the concern. This is one mystery that we are unable to solve. We went through his body for checks - no physical wounds, no bladder infections. And he never bleeds at all. He's back to his usual self but alot glum now because he was barred from the playpen and we officially close the playground until future notice.
In the meantime, he is doing what he does best. ZZzzzzz.