I think it may be candida die off causing your chest pressure. I had a terrrible time with it and recently discovered that Lugol's is great for killing candida. My guess is that it will eventually go away if you continue the Luogl's. It scared me too but went away after I eliminated Sugar from my diet. I currently take 4 drops of Lugol's per day but will only do this for a max of 7 days then take 2 drops twice per week, like Tues and Fri. Apple cider vinegar is also great to take.