Ankle/Shin

I sprained my ankle twice within a year and it took forever to quit aching. Six weeks ago I stumbled and my ankle fell off the curb taking the trash out (I know quit doing chores). The ankle swelled a little bit, but nothing too bad. Since that time my foot has ached (the main pain starts at the top of my ankle/shin bone) and the pain now extends all the way up my sciatic nerve stopping at the top of my thigh. I went to the doctor and he said he felt a mass so he ordered an MRI. The MRI showed a fat ball ( no tumor or mass...YEA!) laying on the nerve. What causes such fat to deposit?...I exercise on a regular bases (been riding bike as it hurts too much to power walk/trudge). Besides massaging, what else can I do to manage the pain and make this go away? I need my feet and legs pain free for a long time. Thank you for your time and consideration.

[Yena H Do, DPM]

physical therapy with peroneal strengthening can help prevent ankle sprains.
fat can deposit anywhere on the body and can be seen on trim and obese people.
if there is a fat lobule on the nerve, have it taken out and sent to pathology to rule out malignancies.  the sciatic nerve pain occurs from an injury higher up (like the lower back).  i would have this checked out to see if something is compressing at this level