It is old age spots
My dog Dirtnap has one of those on his head above his eye. It was really gross at first. I thought it was cancerous since the dog had soo many other issues with him when I adopted him. The previous owner had one removed a few years back on him.
My vet told me that it is an Old age spot and NOT serious. Matter of fact he said a groomer could cut it off. It gets really waxy, black, and sometimes bleeds. It looks like it is "erupting".
I've gotten used to it and it hasn't bothered him too much. I keep it clean as much as possible. I consider it a "pimple".
He's about 12 years old. He's got arthritis, cataracts, and mostly deaf. What's a little spot on his head?
Scooby, Shaggy the "Dogs", Ms. Thang the "Cat" and introducing Measley Weasle "The Ferret".