Chest pains?

I'm 22, and I was told a few months ago when I went for a pregnancy test for my Accutane that I have high cholesterol. At night or early in the mornings, usually when I haven't had enough rest, my heart will "flutter" or race. My mom and my sister both have mitro-valve prolapse, and I was tested for it when I was in high school, but they said I didn't have it. Now I'm having chest pains. I'm not sure how to tell if it's gas or something to be worried about. It's usually at night when I'm laying down, and it happens on both sides of my chest. Sometimes it shoots down my arm, which I know is a sign of a heart attack, but it doesn't really hurt that bad. And also, I had the flu a couple of weeks ago, and my heart rate was 130, and then went down to 120 the next day. I'd taken a 12-hour decongestant at abut 3:00 the morning before I went to the doctor for the flu. My mom said that may have caused my heart to race. Should i go see a doctor about all this? And how do I know if it's just gas?