I am a 48 year old female and just started these problems, ive called the ambulance 4 time this mo.. the only differance is there is no acid reflux present for me.  The EMT's  told me it was my vagis nerve.  It starts as a feeling of almost a heart att.  lightheaded, I feel like im going to hit the floor.It comes and goes , mostly after I eat and while I sleep.  Any way, make an apt. with your dr. and ask them to run test on the Vegis nerve, Ive included a website to check out, u will be very surprized as to what this nerve controls .  Vagus nerve - Wikipedia, the free encyclopedia     The vagus nerve also called pneumogastric nerve or cranial nerve X, is the tenth of twelve (excluding CN0) paired cranial nerves. Upon leaving the medulla ... Branches - Innervation - The vagus nerve and the heart en.wikipedia.org/wiki/Vagus_nerve - Cached - Similar     Good luck and I hope this helps, Im just starting to figure this out for myself..