What Causes Pain, Swelling And Walking Trouble After Fracture Of Bone?

I broke my foot back in october and i was on crutches for 8 weeks. I had small amounts of pain in my foot when i came off the crutches but it wasnt too bad. However for the last 3 weeks i have had serious pain, swelling, trouble to walk on it properly, and a lump in the swelling over the area where I broke the two bones. Do you have any ideas why this has suddenly happened and what I could do to help it?