Having strange balance issue with my back - anyone have a clue

For a month or so I've been feeling an odd sensation in my back. There is no pain but basically I feel unbalanced when I move-  esp. when I'm sitting or walking, I feel like I'm losing my balance. The thing is, it feels likesomething coming from my lower back area - because I notice that I get the unsteady feeling only when I move my back in any way - even if I breathe deeply I'll feel unsteady beacuse the breathing is moving my back slightly.
When this all started I thought it may be some type of vertigo, however I don't get the unsteady feeling with head movement.
What is this and what should I do? (I've already seen my GP and she found no reason for this and told me she doesn't know what it is) I'm wondering if a neurologist would be the right doctor or maybe a chiropractor?
Also I have no history or back troubles or any other major health issues, and I work at a computer for my job.

Any advice would be appreciated! :)

[Adam Tanase, D.C.]

If you decide to go the chiropractic route, here is a referral directory for specialists in Massachusetts - http://bit.ly/cNVofB

[Kabees]

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[Kabees]

Thank you very much.