My puppy is sick and I don't know what to do.?

My puppy is three months old. He's been sick for five days now and he's gotten worse. My mom took him to the vet but all he did is he gave my mom some shots for her to treat him. He hasn't gotten any better. Right now he's been laying down and he can't stand up. The odd thing is that he moves his legs a lot, as if he's trying to move from one place to another. He also makes small grunt noises. He vomited a while ago but I've been giving him Pediatric Electrolyte so he can have fluids. I don't know what I should do at this point. I'm very worried and I haven't slept.