Lesley it sounds like you were already diagnosed with stomach problems. Reflux can cause severe pain, and you can wake up choking. I have to watch what I eat and never eat anything high in fat too close to bedtime, like within 3 hours. Also, you may want to rule out sleep apnea as you can also wake up choking and panicked and unable to breathe with that as well. I really doubt if it is cardiac but it's a good thing you are seeing your doctor. Also, palpitations are extremely common with normal hearts. This forum deals with that topic about 99% of the time. Keep on reading!
I'd be extremely surprised if it was.