How To Treat A Large Bruise Below Waistline And Knee Caused Due To A Injury?

I fell down the stairs and onto the exterior up my upper leg/outer-thigh area three weeks ago. At first it created a giant bruise that spread from 3 inches below my waistline, down to the back of my knee. Now I have a lump that hasn t gone away. Its very sensitive and there isn t anymore bruising. I ve treated it with Arnica gel and not as much ice as i should. Please advise.