Hi! My one year old male cat has this rock hard, dark stuff on his back paw. At first I thought it was dried blood bc every time I tried to clean it up he flinches. He also seemed bit in pain when tht side of the paw touches the floor. After a week or so the gunk got bigger but he was walking just fine. I always let him play outside and im worried tht he might've got smtg from outdoor cats. Haven't send him to vet yet. Im wondering if anyone knows wht it is.