I've had a racing heart due to anxiety. I think I'd explore this since you've ruled out heart disease. Talk to your doctor about the next step for treatment of anxiety. This often includes seeing a doctor (such as a psychiatrist), taking medication and doing talk therapy with a psychologist. It's treatable and you can feel better! In the meantime, try to do breathing exercises when you are starting to cycle to being upset. Breath in 3, breath out 3, hold three. Practice when you are not anxious so that when you are, you can easily do it and slow your heart rate. good luck and keep in touch
Burping being a relief would indicate it's a digestive problem, at least in part, but you're not describing heartburn. It doesn't sound like heart problems, but it could be vascular, meaning it might be circulation problems. That is reinforced by some of the symptoms that mirror that of migraine sufferers, and migraines are a vascular event. Other things indicate possible magnesium deficiency, something pretty common in the US because of the under-consumption of green leafy vegetables and the over-consumption of dairy, which contains high amounts of calcium and not much magnesium and the two must be in electrical balance. But you know, it could be anything. Have you had a physical lately? Do you feel anxious -- anxiety sufferers don't just have physical symptoms, they have irrational fear that gets out of control and that leads to some physiological problems in some. You don't mention feeling anxious, but you might have just neglected to mention it. I would ask, do you exercise? You say you're overweight -- that can produce all kinds of problems in some people and none in others depending on how it affects blood sugar and circulation. None of us here can answer this, but I think you need a better work-up from your regular doctor -- emergency rooms are poor places to get proper care as they lack the time and don't know you.