If you can't beat a problem, befriend it!

You are spending all your energy trying to "stop" what you know you cannot, your random, negative thoughts. Go "with" their punch instead of trying to resist it, let the thoughts whiz right by you as if they are friends on your team at the roller derby meet. Smile at them and "recognize" them; they aren't ever going to let you ignore a genuine health problem, are they? Thank them for their services, for being there. Pushing something makes it push back; "for every action, there is an equal and opposite reaction" (Newton's 3rd Law of Motion).

Make it okay to think whatever thoughts you think and you won't need to think about them so much if you don't want to. That's what most people who aren't anxious think "ignoring" is about, I think, they just automatically don't see some of the thoughts as often because they thing all their thoughts but decide to go on to one's they choose.

Where it gets difficult is that sometimes it is easier to concentrate on worries about problems we can't do anything about or are safe from than to look at and work on actual problems we can work on.

When my husband would go out of town and leave me in the house alone, suddenly I was overly anxious about thieves, murderers, rapists, etc. I had lived alone in my apartment before meeting my husband for 13 years with no problem! That's how I knew my fears were a screen for something else I did not want to consider; being without my husband, being alone and having to take care of myself by myself. I was working on that in therapy so thought of another way to reassure myself when my husband was away; I set up the lighting the same way as it was when he was home and it felt more "natural" to me, like he was just in the other room working when I went to bed.

Maybe you can get an email from one of your doctors and be allowed to send your fears to them when you have them? You could give yourself the feeling someone knew and was aware of your fears so you weren't alone with them, they'd be ready to "help" if something were to happen. I would buy a notebook and keep a fear journal, write it all down, the good, the bad, the things you learn and the things you fear; give thinking about your anxieties a certain time of day each day, let them know they matter (like one does a dream journal; often just recording dreams can make the nightmares lessen or stop repeating dreams because they "know" you are paying attention).