Dog may be hurt, please help?

So my dog was barking and it was really annoying me so I hit it with a broom, but this only made it worse and it started growling and barking really loud, so I hit it really hard in the head with the broom. But now he is acting really weird. I don't really want to take him to a vet because it's kinda expensive, so what should I do to make it stop acting so weird. Thanks in advance for any answers!