Just a shot in the dark here - but if it is affecting your balance, it might be some kind of weird ear infection that is agitating the surrounding areas as well (like your sinuses)
Have you been away on a foreign trip recently?
I'd see about getting the strongest antibiotic available and see what happens after that!
A mate of mine got really, really sick about six months after coming back from Thailand a few years back, and after two weeks of blood tests and lumbar punctures and all sorts of other satanic stuff, he was given a whopper of a course of anti-b's and then it was over as quickly as it started.
They told him that it was probably a very mild infection that was happy to live itself out on the quiet and then something kicked it up to a more severe level.
This might go down as crap to you - but just thought I'd throw it in there!
Hope it works out!
Wayne