1. is he fat? .. fat rabbits don't keep themselves clean 2. is he eating well? 3. if the problem is that he is sitting in his poops.. give him a wire mat between him and his poop. AND clean out his poop more regularly. 4. the smell is his anal glands, you may wish to see if his scent glands are blocked down there. you may find this page helpful: http://brighteyessanctuary.org/educ/rabbit-info-scent-glands.html 5. if you just got him, moving can sometimes cause rabbits to produce more cecals, all you can do is wait it out.