I have weekly/bi-weekly attacks of what I've been told is a-fib. I get weakness, shortness of breath, tightness in my chest, slight dull ache in my neck and shoulders, feeling of hotness but no real sweating, the need to sit down, but no dizziness. I don't normally run to the ER with these symptoms...but honestly, how do I know that they are not symptoms related to an impending heart attack?