Do you have any mosquitoes? The last summer I raised rabbits at my old house, we had mosquitoes and I had several of my rabbits get odd little sores that started out looking like that. It would then develop a crusty dark scab and bleed a little. Once they recovered they seemed immune to it. I did a lot of research and came to the conclusion it's a pox like illness caused from mosquitoes. I didn't have any way to kill or keep mosquitoes out of the cages. They would even get in our house. I ended up selling all my rabbits because it was a terrible place to raise rabbits. They would get sores on their nose and paws, most commonly.