I know exactly what you mean as well. It's really the worst when anxiety takes over...
Something I've been trying and seems successful on varying degrees depending on my anxiety is picking something - a hobby, a website you enjoy reading (that's not health related!), a game you like etc.
In my case I've picked a musical instrument I've always wanted to learn.
If my anxiety starts trying to take my attention - I instead try to focus my attention on my goal of learning my instrument. Instead of googling or even coming on here for reassurance. I either google things to help me prove my playing, actually play if I'm not at work or look through the scrapbook type thing I've made full of theory to help me improve.
I'm not sure if it will work. But I'm hoping eventually when I get the first anxious thought, my brain will automatically make the connection with music and focus on that instead.
With the added benefit of channelling all that wasted energy into seething productive.
I've got a little diary that I use anyway so I've marked a month in there. Every day I manage to divert my thoughts at least once to music instead. I give myself a tick at the end of the day.
Hopefully it becomes easier as I calm down more and more. :p
Just a suggestion but its nice to see all those ticks proving your thoughts CAN change :)