Before I had surgery (probably about 6 years ago) I had just finished dinner at a nice restaurant. I suddenly felt like I couldn't get enough air. I went to the ladies room and back, and still felt badly. I finally felt like I was going to pass out, so I told my husband I needed to get outside and get some air.
I barely got outside, and laid down on the sidewalk. (It was raining...great.) My husband tried to help, but picked up my head, and I went out completely. Someone called an ambulance. My blood pressure was extremely low. It remained low on the way to the hospital. They had me on IV liquids.
I'd just eaten--how could I need fluids? Anyway, the long and short of it--they found nothing at the hospital. After I'd had some time in bed, on IV liquids, my blood pressure stabilized, and they sent me home.
Could the vagus nerve (stimulated by acid) cause blood pressure to plummet? I've never been able to figure out what caused it.