[Sun Tzu]

I had a 2-3 week bout with anxiety a few years ago, and it really came out of left field. Crippling is a word you used, and I think that fits the bill perfectly. I don't envy you right now, but I think one of the most calming thoughts is knowing that it will end. Anxiety attacks/phases are temporary, and despite the helpless feeling that comes with it, there is actually quite a bit you can do.

Cutting out caffeine has been touched on several times, but yes - this is a big one.

Eating healthy is another one. If you're gobbling down 7x your daily sugar recommendations (as most Americans are), then this is actually a bigger problem than the caffeine.

Exercising is huge. The natural chemical euphoria that comes from 30+ consecutive minutes of exercise is irreplaceable, and if you can get one of these in every day, I can almost guarantee your anxiety will begin to fade twice as fast.

Lastly, you may want to look into your state's MMJ laws. A small amount of Cannabis just before bedtime can help squash your sleep woes, and can also keep those "oh shit oh shit oh shit oh shit" voices at bay. I'm not much for chemicals that doctors cook up in a lab, either. I'd rather inhale the smoke of a naturally growing, clinically proven to be harmless plant.