Very unusual, I do not think detoxing is the reason, the skin of the hands is an unlikely place for this. I would think more of something you are putting on your hands, putting your hands in (gloves, dish soap, oils, animal feed, etc) or as you say some type of bacterial or fungal overgrowth which may not be obvious. Nothing else comes to mind. In TCM sweating palms is a symptom of damp/het in the spleen, but that is the palms not the fingers.