Is it normal to always think the worst?

I am trying to figure out if everyone does this from time to time, if I should get it checked out or if I am completally crazy.

This has been a really hard year for my family, my grandmother was diagnosed with ovarian cancer last year in March and she passed away on July 27th last year, my grandfathers house then got broken in to about five months after my grandmothers passing an the burgler got away with a bunch of my grandmas jewlery and the money my grandma and grandpa had saved to go on a cruise together (which she couldn't make because she passed away). Then a few weeks later when my grandpa gave a few things to his sister of my grandmothers as a keep sake and when she headed back to B.C her house then burned to the ground from arsonists a day after arriving back at her home.

So my question is a) is it normal to believe that because all of this happened to my family that something will happen to me? I am completally paranoid now....the minute I get a headache I think to myself OMG what if I have a tumor or something??? And before I leave the house I now need to double and triple check that all the doors are locked, stove is off, my puppy is fine etc.....

And b) for all those who believe in spirits or ghosts; is this a sign??? Is my family doing something to make my grandmother unhappy?? Does she have unfinished buisness??? Is she the one that is causing all this???

Please share your stories if you have any!!!
Much appreciated!!