question: My heart has been racing, then slowing greatly, and I have been dizzy, and have a shrill throbbing/pulsing, ringing in my ears. I am 48, f, and this has been going on for several months. I frequently have chest pain, but have recently, during a visit to ER for other causes, had heart testing, that \"looked good.\" Can you tell me what might be the problem? This pulsing is in time to my heart rate. Thank you.