If it's causing you difficulty functioning, I would absolutely talk to a professional about it, so that you can learn coping mechanisms for dealing with these sorts of things.
Honestly, your child had a FAR greater chance of being killed in the car on your way to Target. And yet we don't freak out about those sorts of things.... well, for a number of reasons, some good, some bad. It's normal to worry, just not normal for it to take over your life.
I know there is nothing I could do to prevent whatever unexpected, rare tragedy were it to come up. That's the whole point. And I would do my daughter a FAR greater disservice to make her live in fear, closeted away from the world, due to infinitesimally small chances. And what if I did that, and then something bad still happened? She'd have a short, unhappy life, rather than a short, happy one. So, just like I want her life - however long it may be - to be happy, I have to live the same way.