Hi - I have not used Candigest, but do use Candizyme and have used Candex which are also enzyme-based antifungals, so basically the same thing. I am not sure about the constipation. It has not affected me that way. And, I have not had the burning/soreness you describe. But, I will say that I don't think that one day is enough time to be experiencing die off from this product. It works more slowly than other antifungals, and I have never gotten die off from it until after about 2 weeks of use. It does sound, tho, that your liver is stressed, which in turn can cause the burning/sore stomach (is it on the right side near ribcage?) and also constipation. Maybe try drinking a fresh squeezed lemon in your water throughout the day to help your liver deal with it. If it gets worse, I would consider stopping it and trying something else instead.