If you keep worrying about different things all the time, it might be helpful to look back at previous worries and remind yourself that they were false, so this one probably is too. (Not so good if you worry about the same thing all the time!)
For example, most recently, I have worried about breast cancer, MS, bowel cancer, heart attack, MND, brain haemorrhage, brain tumour and the latest one was stomach cancer. I just point out to myself that the other 'symptoms' went away and I'm not worried about them any more, so the 'symptoms' of this latest 'illness' will probably go away too, and if not, I can go to the GP next week...of course, by next week, I have a new range of symptoms and a new illness to worry about, so I repeat the conversation with myself.
Funnily enough, when I'm really ill, I don't have any health anxiety. I started a cold yesterday (soon as I'd got the Christmas dinner served, I started a sniffle and sore throat!) and am now coughing and sneezing all over the place and not worried about my health at all... It's a solution - of sorts - but I'm not sure I want to live with a permanent cold