How To Cure Rough Dry Brown Hard Spot On Top Of Right Foot?

Hi, I am 32 years old and recently found a rough dry brown ..almost hard spot on the top of my right foot.... i had it check by my regular doctor and he told me it would go away with a cream....its been several months and it is still there like the day it showed up.... what could it be and do you think i need to worry bout it.... i dont have skin problems in my family history and have never had anything like this before...