Years ago, we were playing very regularly. My fingers started breaking out with dermatitis. In between my fingers became inflamed and sore and eventually, the skin would burst and I would bleed. I've actually played with blood running down my hands! I had to find out what was causing it. I tried at work to get tests done, but that never came to anything. Eventually, I worked out for myself that it was the nickel strings that I was allergic to. I changed to stainless steel strings and have had no problems ever since.