Likely there's something up his nose. Examine with a flashlight and, if you find something, go slowly and gently for the tweezers. if you can't see anything, either buy an otiscope and try again, or better, head for the wet. Removing vegetation from a dog's nose is usually very inexpensive for you and very comforting for the dog. Foxtails are a classic example of a barbed plant that can lodge in a dog's nose.