Over the last week, I have begun to itch uncontrollably on my entire torso and head. Benadryl helps temporarily but I am constantly feeling the urge to scratch otherwise. There is no visible rash or hives. Aside from that, over the last few months, my thumbs and index and middle fingers' nails grow out slower than normal and have become brittle, and the index and middle fingers' nails are flattening in shape. Could I have cancer, diabetes mellitus, or liver or kidney disease?