What Causes Soreness, Toughness And Pain On And Between Fingers?

I have a spot on the inside of my ring finger between the middle and ring finger where the skin has grown tough like a callus but it never goes away and I do not do anything physically to obtain the callus. The same thing is on the inside lower digit of my thumb on the same hand. On the thumb however there has been a soreness and I have to put vaseline or triple antibiotic cream and a bandaid each to keep the lubrication on that area or the thumb has cracked and then it really hurts. Again I do not use that part of my thumb on a regular basis. Do you have any clues as to what it is and should I be worried enough to go to a dermatologist? It has lasted for a few months.