@turquoise-- I have no idea. Can you take the dog to a veterinarian?
I would avoid giving the animal any antibiotic without being prescribed or recommended by a vet. Especially clindamycin because it is not a general use antibiotic. It has a relatively narrow use, it's for soft tissue infections and is mainly prescribed for mouth infections.
Once I have heard of it being given for an ear infection, but usually a different type of antibiotic is preferred. Also, you have no idea what kind of an infection that dog is dealing with. Giving the wrong antibiotics will make him worse off because the bacteria he does have will become more tolerant of antibiotics. You will reduce the likelihood of antibiotics helping him in the future.