My dog has been so clingy lately I can’t even get a picture of him without having to include my leg in the shot. What causes that? When I go outside, he sits by the door until I come back. Right at this moment, I am covered in dog. It’s too hot to be covered in dog, why me?

Seriously, anyone know why dogs sometimes go through clingy stages? Should I be taking him to the vet? He seems fine other than the clinginess. :/