Does anyone know what this little tiny ,thin,black or brown looking bug is that's crawling on my yorkshire terrier,its slender looking and either black or dark brown,there's not a lot of them,just a few,but they crawl on his skin very fast to where I can't even grab him,I have another dog,a short hair brendle boxer,and he doesn't have any,I've shaved my terrier down and flea bathed him 2x now and I don't want to do it again for fear of making him sick,can anyone help?

MY dog has these little black or brown bugs underneath his stomach. They are not fleas either. Have administerd flea and tick medicines and even given him flea baths,sprayed him, even powdered him down but still see three or four bugs on him sometimes. Little patches of black minute dots also on him, don't know if these are eggs or not. Help!!