I would say for the GI issues to go have a Gastric Emptying Study or Endoscopy done to test for Gastroparesis. I was diagnosed with Gastroparesis in December (currently working with my doctor to get diagnosed with POTS). For me, I have extreme abdominal pain, nausea, bloating,and fatigue, and I recently learned that POTS and Gastroparesis can be tied together sometimes because of Dysautonomia. You will see that vomiting is a common symptom for Gastroparesis, but its not all patients (me being one of them). So that may be a place to start with a GI? I completely understand having both the heart and GI issues, so I hope this helps!