it sounds like callus buildup. when i first started
playing guitar my fingers would get extra skin that peeled, and after being around other musicians, i was told the fingers build calluses because of the strings, which explained why when i first started playing, my fingers were really sore, but once i got calluses, the strings didnt hurt my fingers anymore. i did end up with really thick calluses on my fingertips, but i loved playing guitar, so i didnt mind.