Girlfriend accidentally received 3X allergen dosage by new nurse

My GF recently went to get her immunotherapy shot shes been taking for the past year, only to receive a call when she's on the train home asking if she's ok because she just accidentally received almost 3X the dose she should've. 40 minutes, 2 epipens, intense pain, weakness, and an ambulance later, we're at the ER and she finally begins to feel better. Doctor said it could've been an anaphylactic shock. We want to pursue and are looking into medical malpractice attorneys.

Any tips as to how to go about it? We have minimal legal experience so even suggestions on how to determine the best attorney would be helpful. We just reached out to the NYC bar association and scheduled a call for some guidance.