Broken Ankle-complete break of lateral malleolus

Hello,
Almost 4 weeks ago I broke my right lateral malleolus. 1st doctor said it looked like a very old fracture on x-rays. Second doctor said it looked like a very old fracture OR possibly an extra bone I was born with (accessory bone.) He did see a small fracture on the malleolus , aside from this other piece of bone that he wasn't concerned about, so he sent me home with a moon boot and no follow up. A week later I went to see my doctor and he was unhappy with what he saw on the x-rays. He felt that "extra" bone was a fresh, complete break of the malleolus and said he would have "pinned" it, but it was too late. X-rays performed today show that this bone is indeed healing. So my question is, why did other doctors think this was a very old fracture or accessory bone?? And, can a very old fracture show healing if the foot is placed in a moon boot???