This happened a couple of months ago. My dog has recently been biting the area right above his tail. It isn't ticks or fleas, we have ruled that out. He knows he is not supposed to do it, as last time this happened he ended up making a gash in that area. We always make him stop when we see him biting it and will scold him for it. He has gotten clever about it though. When we let him in the backyard to go to the bathroom, he will go around the corner and bite it there. He will move to a room where no one is on purpose. I don't know what to do. He has not injured himself yet, but it is just a matter of time. Please help!