(((lost))) I'm so sorry to hear how much this anxiety is upsetting you. IMO you're thinking such terrible fears because you do have anxiety. Others get though this a few ways<ul type="square">[*]go to talk therapy and learn how to ground yourself[*]take medication to help you while you learn how to calm yourself[*] both of the above[/list]
Anxiety can cause vertigo, especially if you tend to hold your breath, which many of us with anxiety tend to do. Therapy is hard work, it's even harder if you won't allow a doctor to talk you through it. What else have you tried, in solving this?

There's probably nothing wrong if doctors have checked you out. I would try some things specifically for anxiety first, then if they don't help go for the cat scan. I know good therapy will give you relief, at least in worrying about what if... and will allow you to plan on how to be sure. TC