Vet! ASAP! Concussions, etc can cause permanent brain damage if not treated.
How did the dog "fall" out of the truck? Have they taken the dog to a neurologist? ... I know the answer to that one ! And I hope these responsible people don't have children.
I think you'll just have to give it a lot more time and see what happens. So far, it seems to be mostly good news as she's showing some improvement. Has she been to a vet?