Hi @cherawgirl, so sorry to hear of your problems with fainting going on for so long.
For nine months, in the throes of an autoimmune disorder, I had gagging attacks without nausea. They did go away before I started on steroids, but they were debilitating. At the time, I researched a lot of exercises online and ways to reset the vagus nerve. Have you ever looked into those? Maybe they could help you.
There's also work by Dr. Stephen Porges, "The Polyvagal Theory". In Dr. Porges words, "the perspective placed an emphasis between psychological experiences and physical manifestations in the body." It might be worth looking into Dr. Porges work, as he is compassionate and insightful, and who knows, maybe it could help.