Think about restricting your diet to all natural foods. Veggies, fruits, meat. No sauces of any kind, no sugar, no caffiene, or anything. 5 days should work to see if you notice a difference. Then you can add things back in slowly but surely to see what is the problem. You have to be extremely strict for the 5 day period. .
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Try to remember that your brain controls your body and you are in control of your brain.
If you make a conscious effort to control your thoughts you will find that you can ease your panic and episodes of anxiety.
I wish you the best and know you are not alone.