Suggest Treatment For Severe Dry And Cracked Skin

Hello, I have been having severe cracking of my skin on hands and feet. It has been over the past 1 1/2 years, and is getting progressively worse. My feet are cracking very deeply, and my hands have several oval-shaped patches of dry skin that sometimes split but are mostly just raw/tender under the dryness. Most of the cracks/splits are on fingers, above the nail toward the first knuckle, and are often swollen. I have tried Clobetasol, which does not seem to help at all. The most effective treatment has been soaking/spraying with 100% white vinegar, twice per day. If I miss a vinegar treatment, the cracks come by the following day.
Do you have any suggestions as to what this might be, or what I can do for it? I am 40 years old, and have always been prone to dry skin, but had never had a deep fissure in my life until January 2010, and continuously since then.
Thank you for your help.