I had episodes of panic-like feelings where I felt suffocated and hot and could feel my heart pounding throughout my body and tightening in my throat. Last year after 2 emergency room visits and many tests, heart problems were ruled out, and my doctor prescribed atenolol (now metoprolol) to relieve symptoms. After awhile, the symptoms are returning in a mild form. I thought I needed to stop the meds, but it seems taking half a tablet on one day greatly increased the symptoms. What is the matter with me?