S.T.
This probably isn't much help...but here it is anyway.
My daughter used to do that too. So much so that she would fall down on the hardwood floors in my house and bang her head so it would crack open and bleed. I even tried putting her in her room, but she would run at the door and whack her head on it. I pretty much didn't take her anywhere for the first two years because she always had a bruise on her forehead and I was afraid people would think I was beating her! I tried everything...and nothing seemed to work. Eventually she just stopped. I think she was around two and a half. It was very frustrating, but she just stopped on her own.