Xylene

I've smoked marijuana on and off, probably a total of 15 times but I still get insanely paranoid when I do it. I am not afraid of getting caught, I just think I'm going to die or something, like I'm going to have a heart attack (which is crazy I think). My heart starts racing and it just scares me even more. My head feels like it's being put in a vice and I feel a lot of pressure. It usually only happens if I'm alone and high, though a few times it has when I was with others. Sometimes I don't feel paranoid at all, I just feel great.

As far as I know I don't have any health problems, I'm in average shape (5'10", 145 lb), though not very active.

In your opinion, do you think this is just something in my head that's making me paranoid for no reason or there could be some sort of health issue and that I shouldn't smoke anymore?

This might not be the right place to ask for advice, but I figured it was worth a shot. Thanks in advance.