My dog bit my vet and vet tech

We are devastated. My dog (5 year old intact male Golden retriever) bit someone over the summer. Our friend laid down on top of him And wouldn’t get up and our dog bit him. We took our friend to the ER, reported it. Friend is ok. Now today, I take my dog for a regular check up. I explained about the bite and how it happened. My dog was fine with the blood draw and the exam but once the vet started his vaccine injection, he flipped out and bit her. When the tech tried to step in, he bit her as well. We are beyond worried for the vet staff and we are devastated over this. I have ordered a muzzle. I don’t know what else to do. Has anyone had this happen? Thanks in advance!