What is wrong with my dog?

Lately I've realized that he won't walk or drink out of his bowl. We took him to the vet & they gave him some shots & injections but he's still stumbling when he walks. He also cries whenever we pick him up & he just lays there all day /: I don't think he broke his leg because he still walks on it but he did fall off the sidewalk a few days ago. Can you guys please help me? He still walks on that leg may e it's sprained? The vet didn't tell me what was wrong with him they just charged me a ton of money. How can I treat this?