I wanna say ticks. When my mom and I got my dog he had ticks and we didn't even know. I even pulled a few off myself, my mom has Lyme's disease cause of it too.
We got rid of them with simple tick shampoo and a few bug bombs. :/
If you do that, the head will still be in the skin and the tick will re-grow. You actually have to burn them off. My dog used to get ticks in his ears when I took him hunting in the woods, and my dad showed me how to burn them off. Shampoos did not work. Be careful not to burn your dog!! Singeing a little fur is normal, it will grow back; but be careful of the skin. Once the tick feels the fire it will loosen it's bite and you can pull it off, it might even pull its head out of the skin on it's own
We just wedged them out with a needle.