constant fear of dying

I am so frustrated that I cannot move past this fear of dying.  Since my anxiety began six months ago I have diagnosed myself with bone cancer, breast cancer(multiple times), brain tumor, blood clots in my legs and just when I thought I was getting through all of this I read an article about Ovarion Cancer and can't get it out of my mind.  I now have all of the symptoms of it and am scared to death.  I can't stop goggling symptoms or going on webmd even though I promised my therapist that I wouldn't do that.  I am so sick of feeling this way and starting to feel like it is never going to get any better and that I am going to live in constant fear.