I have a 13 month old puppy named Duke. For quite some time he has be nipping himself on his back and back legs, becauswe hes itchy. When he was at the vets they had done a skin scrape and found no perisites or mites etc. I was told it was most likely an allergy. I know that most allerigies in dogs are from their food. I had just changed his food over a month ago to an organic blend. he had to be on predizone, and it seemed to help but i know its not good for him. So right back it started up again. And now he has a large red bump on this back leg. it looks very painful and I have no idea what it could meant. I know most irritations comes from either insect/fleas or sometimes an irritation to the changing of seasons, but this has been going on for quite some time. Anyone have any suggestions as to what this might be?? it would help alot. Im a little nervious, I hope its nothign serious.