If you notice black things embedded on your dog's skin, then this could be one of two things in my opinion - blackheads or fleas.
I wouldn't recommend squeezing them because it could cause an infection but do the black spots look like those in the photo above?
If so give him a good wash with some doggy shampoo and he should be fine. It is just dirt under the skin and is very common, especially as it is not a good thing to bath a dog too regularly. My dog's groomer only likes to see her every 3 months!
If there seems to be black bits falling off the dog, it may be flea dirt, in which case it is just a case of a simple flea treatment which you can buy at any pet store or get from your vet.