I found a wasteland dog that was wounded. I healed it and had a brief dialog with it. Now its following me around and I can't give it any orders. What's the deal with this dog?

Its name was Mutt. Seems like I lost it now.

Did you have dogmeat or another companion with you? I think that causes a bug with the dog. Others are experiencing the same thing- https://steamcommunity.com/app/377160/discussions/0/496881136904336878/

I had Codsworth. I lost it at am intersection where there was a bunch of cars. I went back there later and it was gone. In its place was some dude selling a dog. Which I didn't buy.