HI and thanks for using the forum.
The EKG and blood work that is typically done in the ER will tell you if anything acute (immediate) is going on with your heart. The EKG checks your heart rhythm and the blood work that is usually done checks things like your heart enzymes.
Acid reflux can cause chest pain and it is not uncommon for someone to have reflux symptoms and think that they are having a heart attack. Are you being treated for your reflux? Is it under control? It is possible that your stress and worries are causing your headaches and reflux. I would suggest seeing your general practitioner and having your reflux evaluated. If you get that under control, your other symptoms may subside. I would also discuss your other symptoms with your general practitioner. He or she may be able to help you put your mind at ease either by reassuring you or by ordering further tests to rule something else out. Good luck.
Bridget
You sound like a reasonable person, and you seem to think something is physically, not emotionally, wrong with you. Go with your instincts. You were diagnosed with anxiety and panic attack. High cortisol (an adrenal problem), for instance, can create anxiety that will cause panic attacks. Your fatigue may be from the same cause. Or not. In any case I would see an endocrinologist.