Suggest Treatment For Neck Pain After Injury

Hi,

Approx 3 years ago i was walking down my stairs and got the 6th step from the bottom my heel clipped the edge of the step and i slipped and gathered up speed to which i fell on my bum at the bottom of the stairs. i felt an immediate pain shoot up my back right to my neck. i got up and was ok. the next morning i woke and i couldnt move my neck. went for an x ray and nothing showed up. went to physio and it helped a bit. i have suffered since then but it seems the past week or so it feels the way it did when i originally injured it. i can move my neck no problem and but have a constant pain but when i sit for long periods of time which i do as i work in an office at a desk the pain increases. it feels like pressure pain. i am 29 years old and 5ft 4 female. any advice appreciated