Hi, i have had sudden palpitations starting with a warm sensation from head to toe , then my body starts shaking and i feel like i can t breathe and i need air. i usually have to go outside, but then my body gets really cold . i feel very weak and like i m going to have a heart attack . i don t take any meds. no alcohol or drugs. i do have a cup of coffee every morning, but i ususlly don t even finish it. i went to the emergency room the first time it happened and they did an ekg , bloodwork and catscan, all normal. then i saw a cardiologist , i did an echocardiogram and a halter monitor, all normal. but i am still experiencing this from time to time and my heart usually feels weak a few days before it happens. my left arm is numb right now and it happened a few hours ago. one of the worst! every time it happens i was relaxing or standing up putting on makeup one time, but not at stressful times. just want to know if i should get more tests done, because it really feels serious when it is happening! Thanks. Diana