Swelling under right foot Ankle

For last two months I am suffering of swelling under my right ankle. My x-ray is clean and now my dr. thinks it's a contusion of bone. The swelling is localized under the ankle. There is no problem with Ankle. This injury started when I was painting for long hours for at a least a month or so. without shoes. I have flat foot and can feel some heel spur pain. I am wearing orthotics now but my pain/swelling which is localized under ankle is not going away. Also when I walk and move around for few minutes I can feel pain in back and hip. I have taken anti -inflamation drugs, Done R.I.C.E but so far no results.Is this a known problem and what can be the best way to recover?

Can you clarify where the swelling actually is. Is it under your heel or around your ankle? Was there any injury or change in circumstances that caused this problem?

If you can expand a bit we may be able to assist better.

Swelling is just under my right ankle (outside). Most of the pictures I have seen show that this looks to be area peroneal tendon area. I have redness and swelling. My doctor gave a corticosteroid injection on the inflamed area. I had no injury. The only think I can think is that I was painting my basement for long hours barefoot on hard wood floor. Also I have flat foot. I have anti inflammation medication for almost a month. Will start physio. in couple of days. Not sure what can I do. My Dr. is not really able to figure out the exact cause.