If it starts as small blisters that then dry out and your skin cracks, turns red and itchy, I had the same thing for years. Dermatologists had no idea of what my problem was. I took my daughter to the hairdresser for a cut when she was 7 and she recommended a product called Cure Care for dry scalp. After using it on her for about a week I noticed my hands cleared up. As long as I used it I had no problem with my hands. When I ran out, my hands particularly my fingers blistered again. I have used this for over 30 years. You might want to try it. It is available at Sally's Beauty Supply and it is not expensive. If you don't have a Sally's near you, try the website. It's also great for your hair. I know it sounds weird but it really helped my hands.
Have you tried using tar compounds on it? This can be purchased OTC in the USA.