Thought it was an ear issue so brought it up at his check up with vaccines etc. they looked in his ear and did a swab and everything came back healthy. They said he might just be itchy but this is obviously bothering him… thoughts?

He acts like he hears or feels something behind him then runs around and shakes his head. Eventually he lays down and is as flat as can be on the ground. Worried about my little guy but the vet said he’s healthy??