I'm really worried what should I do?

A few months ago my stepfather passed away from a massive heart-attack. His heart had swelled up and there were three blood clots. We think this could've happen from taking to much muscle relaxers. He took them because he would get a lot of tension headaches and he thought by taking those it would maybe loosen up the muscle would go away. But there was this warning on the bottle that said something along the lines that it could cause heart problems and my mom told him that they aren't good for the heart. But he ignored it. Well last summer around my birthday in August my biological father had died. Also from a heart attack. He had a bad heart. He had multiple open heart surgery's. He was also a diabetic. He didn't take good care of himself. He would eat a lot of sugary foods. He was a recovering alcoholic too. So that wasn't really good on his heart. Well like a month after my step dad died I would get these pains in both of my arms on and off. And I know one of the signs of a heart attack is I think right arm starts with pain. Or it could be left I don't remember. So I would start to freak out and think 'Am I gonna have a heart attack? Am I gonna die.' And just to add I'm not a hypochondriac. I started to act like one though. I know how they act my friend is a big hypochondriac. But before the deaths I had no problem with death. I wasn't afraid to die like some people. But now I am... I've dealt with deaths before these 2. So it's not my first time handling it. I've been scared lately that I'm gonna die of a heart attack. I don't know why. Is it part of the grieving process or something? Could someone give me some suggestions? Thank you. By the way if it helps I'm 16, soon to be 17.