Once again ginger is correct. These are signs of central nervous system swelling and should be monitored and treated.
I second that.
He will have had some concussion, and that can cause vomiting, dizziness, lethargy etc.
But the thing you need to be careful of is if there is any bleeding going on. Waiting to 'see what will happen' is maybe not such a good idea.
Take him to another vet as soon as you can. I think that's the wisest thing.
I would get him into a different vet. It sounds scary to me. I am new here, but have had dogs all my life. I wish you well. Marie