Accidents happen, and so do health emergencies, and emergency room doctors see it all, big and small, every day. Because of this, they know simple mistakes you can avoid that can cause serious health problems or even put your life at risk. Here are five crucial things an ER doctor says you should never do. Don't ignore chest pain Chest pain can be a sign of a serious condition, such as a heart attack or a blood clot in the lungs. Other symptoms include shortness of breath, sweating, nausea, and/or pain ...