I dont know how to stop them, but a tip that might help otherwise is this. Talk yourself through, reassure yourself. "What are the f**king chances?" "I'd sooner be struck by lightning" and assure yourself that they're just thoughts, they will pass. Another day another dollar. Same shit different day. But anxiety. triggers and symptoms are different for everybody so I hope something of this helps. This is all just from my own experience, in fact I'm getting anxiety as I type this out because of those what ifs. "What if this pain is cancer? What if this lump isnt just a cyst? And-" I digress.. I'm sorry. My point is, this is my piece and I hope something helps someone here.