You need to take your dog to a vet; plain and simple. Trauma to the head, let alone the entire body can cause anything from brain and organ damage to neurological disorders (especially in developing puppies, let alone a 4 week old one).
I truly hope you either find a vet that will work with you on money or find a way to obtain it. You're not going to find a solution or answer here.
If your timeline is correct, you had the puppy at 4 weeks old or younger? You don't sound like someone that should be handling a pup that young.