What Causes Lump On Skull Base When There S A Headache?

Hello, I am a 26 year old female, 5 6 126lbs, non smoker with a relatively healthy diet. I do not have a history of health problems, but have been getting severe tension headaches for the past 12 years. I tried talking to my doctor about it a few years back but she only told me to keep a journal of when they occur which only showed that they begin anytime, anywhere, with any activity. They have gotten increasingly worse over the past couple of years sometimes occuring on a daily basis over several weeks and now being accompanied by a hard, ping pong ball size lump at the base of my skull that is bigger the worse the headache is but disappears completely on days with no headache. Massaging it does little good as it is too hard, but occasionally taking a nap with a heated rice bag under my neck will somewhat relieve the pain. I also feel the pain in my temples when I get the headaches. I ve tried relaxation techniques, yoga stetches for necks, an array of over the counter pain killers and chiropractic care, nothing stops the headaches. I can t function like this anymore, a single headache completely drains my energy and my brain just always feels foggy trying to think through the pain. I can t bear the pain anymore but I don t have any idea how to make the lump go away and stay away & keep the awful headaches away with it. What specifically could be causing the knot and what would be the best way to relieve it and prevent it from returning? Any help would be GREATLY appreciated!!!