I Fell And Injured My Forearm Close To The Elbow

I fell and injured my forearm close to the elbow about a week and a half ago, small scratch and bone bruise. About five or six days ago a small knot appeared and it became painful and more swollen than when it happened. It also became hot. The pain and swelling subsided a lot in the last few days but today is worse. I started applying heat today. Will this run its course with regular heat or should I get on antibiotics?