I'm so sorry that you and your baby are going through all of this. Through the years none of my Yorkies have had a Corona, Leptospirosis, or Bordadella vaccine. My Ashley was diagnosed with an enlarged heart and mild collapsing trachea when she was almost eleven, and my vet stopped all vaccines for her. She lived to a month shy of seventeen, and even though we took long walks daily and saw many dogs, she did fine. It sounds like you are very happy with the specialty hospital that is treating Nicky. If you need another opinion, you can try Animal Medical Center in Manhattan. It is the world’s largest hospital for small animals and is a leading center for research, clinical advances, and veterinary medicine.
Animal Medical Center - New York City Specialties & Services | Animal Medical Center
I will pray for both of you. I hope Nicky gets well soon.