Hi Doctor, My 4.5 month old Golden Retriever puppy suddenly developed bulge on his back under the skin. It’s visible from outside. It’s soft and moving when touched. We are sure it was not there before. Is that something to be concerned?Another thing, He was playing with other dog yesterday morning when he felt hard on his back. Is it possible to develop bulge from that? It doesn’t feel like swelling bone and when touched he is not cranky or not in pain. He is active & playing.