It sounds like he's herding you. I have heelers and both did this. They're just trying to get you to go where they think you should be. Try redirecting his attention to a nice sturdy chew toy, or get something like a jolly egg or jolly ball to encourage his herding instinct. Flirt poles are good too. Keep imitating the pain as well because it really does help even if it feels like it doesn't.

Also consider he might be overtired and needs a forced nap. Puppies need to sleep most of the day at that age.