How To Treat Pain And Swelling Of Radius After Undergoing Surgery?

I had surgery in late 2009 to repair a fracture of my radius. Titanium plate and six screws were used. I get pain and swelling still especially if I use my arm a lot even like vacuuming , scrubbing things , lifting things, playing ball with my daughter. It really has gets uncomfortable. Why do I still have this pain and swelling ?