I've certainly had, and frequently have this fear.
It stems from an OCD fear of death, that's what causes all of these health worries.
I've also had immense fear of having a blood clot, so much so that I had to walk for at least an hour and a half a day in rediculous hope that this would some how prevent it, haha.
I also have POCD, have for about three years now.
Like otter said, though, all we actually have is OCD.
The themes are names we've given them on the Internet and around forums like these to quickly give a name to the situations we're feeling, but they're all the exact same.
My girlfriend has ROCD. Fear she's not good enough to be in a relationship, all stemming from low self esteem.
At the end of the day, OCD affects everyone in different ways, although, we all are doing exactly the same thing and worrying in the same way.
It's best to just look at it as OCD rather than looking at the theme.
To get rid of it, you need to identify it as one.
If you have POCD and fear of death like me for example, you need to just think of both as OCD, because trying to treat the themes won't work.
Look up ERP therapy. This is currently the road I'm going down to get better, and has had many successes.