Hello, I understand your concern. From your description, you seem to be suffering from a case of eczema, i.e. hand dermatitis, caused by exposure to constant irritatants. I recommend you stop using any harsh chemicals, soaps, shampoo or any hand lotion you might have been using in the past. When shampooing your hair use gloves and use e mild soap as a hand wash. Also, make sure you completely dry your hands after washing them. It would be best if you stopped playing guitar for a while in order to give your fingertip skin a break from the constant irritation. If this condition persists, despite applying these measures, please see a dermatologist. I hope this helps. Wishing you all the best.