Hi, did you test with urine pH strips? I've been finding that sometimes it takes a lot to get the color to move to the blue end, much more than usual. (Always on an empty stomach, of course.) Then the next day, things will respond normally. It seems as if sometimes I get a real buildup of acidity that needs to be tamped down. Do you get that crushing feeling of pressure in the chest during cold immersion? I don't know how that might relate, but I do think that I might get it more strongly than average. Have you alternately tried lots of antioxidants beforehand? Or anti-inflammatories?