Could be anything from wind to gallbladder to heart attack - not to worry you but really you should phone emergency for advice asap!
I wish I had answer. I have had the exact same symptoms for the last week. Been to ER, thought heart attack, blood and ekg were normal. Then went to Dr waiting test results from stress test. This is not anxiety or heartburn, symptoms sound the same, but they feel much different than both. Dr isn't quite sure. I have had very high blood pressure since giving birth 3 months ago, also was diagnosed with Bells Palsy 3 days after birth and almost fully recovered from that. Heart rate stays around 100 bpm and bp usually stage 1 or 2. Never had heart or bp issues before this pregnancy. Any one had this or knows what could be the cause?!?!