Hi Sweetie UK,Prior to my surgery I had an episode that was never explained, but I think was likely vagus-nerve related. I overate in a restaurant, and became very light-headed. My blood pressure lowered and wouldn't increase, so I ended up being transported to the hospital. They hooked me up to an IV, but never figured out what caused it.
The vagus nerve can definitely trigger fainting spells and light-headedness. Here's a link to some information on the topic:
en.wikipedia.org/wiki/Vasovagal_responseGood luck with it all!
Best wishes,
Denise