Before I was diagnosed with PMR and GCA, in addition to most of the usual symptoms, I had about 29 gagging attacks over six months. They would occur at the same time everyday, with a funny feeling behind my navel, profuse sweating from a point on top of my head and a convulsive-like gagging reflex in a straight line down the front of my body with vomiting and diarrhea. Sometimes these attacks would put me down for the day. I started researching the vagus nerve and did all the exercises I could to reactivate it. There's a lot on YouTube, plus I bought the book, "Activate Your Vagus Nerve" Dr. Navaz Habib on Amazon.
The attacks stopped about a month before I was diagnosed and started taking prednisone. I just took a look at Dr. Habib's book, and there's a diagram of the vagus nerve on the cover. It shows it extending up both sides of the head, ending below the ears down the neck and into the shoiulders. I never realized it before, but those were the exact places I had neck/head pain, so severe I could not turn my head. That pain didn't stop until I took prednisone.

I've never seen a post about gagging attacks with PMR or GCA. They were a horrible symptom.