What Causes Swelling Below The Neck Along With Headache?

I have a large swollen mass at the base of my neck. It swells during the day and gives me serious headaches.Some times my muscles have
Locked up and I can hardly move my head. My Dr. Has said it is a buffalo hump caused by fat distribution, I have gained weight steadily this past year, much to my frustration. I am 40 lbs. more than I should be! I don't feel this is normal or ok! Besides constantly trying it lose weight, what can I do! By end of day I hurt so bad I can hardly move!