Hi there. I have this fear too, thought it does not manifest that often. The thought of it just pops into my mind every now and then AND it scares me. A lot. It also occurs when I'm in closed places since I am claustrophobic. But I tell you that it's normal to have fears, we all have them, and let us just live life as it is. Fears hold us back but it can make us stronger. You should talk to a psychiatrist about this if it gets really extreme or better yet, consult one now. I understand your situation as I am suffering for many phobias and fears for a while now. I hope you will do well, friend.