Why There Is A Big Bump On My Fibula After Tripping Over A Limb?

I tripped over a huge broken limb while running around in the woods, the limb made an indent in my leg kind of like a scar. At first there was no pain. A few days later my ankle had swelled up to twice its size& a bruise wrapped all the way around it.. Now that the swelling has gone down there is still bruises and I have difficulty walking on it, there is a really big bump on my fibula. What could this be?