It looks like blood under the skin. Did he have immunizations recently? It does look like bleeding under the skin. Check his mouth and ears for blood...and stools. Sorry if this all sounds scary, but it seems similar to what Lucille, my Newfy-girl had and it ended up being ITP (immune-mediated thromocytopeni a). It's probably something else all together but that's the only thing I've had experience with. Check his ears and mouth and stools. If there's no blood, then it's probably something else. Got my fingers crossed~!