I had this for a year at least, it was constant. I related it to inner ears but could never figure out if I had a virus or what the deal was. Do you have any ear symptoms? I had things like fullness in and around the ears, muffled hearing, plus my tmj disorder was irritated causing headaches and occassional ear aches. Getting my tmj disorder under control helped the situation but did not cure it, I'm positive that whatever the problem was it was setting of my tmj spasms not the other way around. It also came back once but not as bad.
