Definitely go back to the doctor. It sounds like you had a scaphoid fracture and these fractures are notorious for being poor healers. If it is not adequately healed you can refracture this bone and because of a weird twist of evolution, these fractures can sometimes lead to interruption of blood flow to part of the bone resulting in permanent bone damage. So, even though it's a crack, get it checked out!

I had one of these, funny story how I got it. But it took 8 weeks of immobilization to heal, then about 4 to 6 weeks of PT to get to about 90% of normal function.