Let me guess, because you are possibly under 40, no doctor has checked your hormones levels? I say that because too often, doctors ASSUME, because a woman is under a certain age, they don't have to check hormones. I mention hormones, because at the age of about 39ish I began to have bouts of Vertigo .. This, out of the blue.. Having NEVER had it before, I chalked it up to STRESS (which definitely doesn't help matters) later on and with no help from doctors, I began to read up on matters and found that in my case, it would seem that the severe fluctuations in Estrogen/Progesterone ratios (which I knew had happen because I did happen to have a hormone test for other reasons) might well be the culprit. While I don't have the Vertigo like I once did, even just a few days go when my my Estrogen dropped off (I track my monthly cycles) I did have a dizzy spell....
Again, the highs and lows of hormones can cause such problems..
I would definitely suggest that someone do a hormone check... Also, go online and check out Dr. Vliet. .she has done a GREAT deal of hormone research and has had so many patients come to her after no other doctors could figure something out. Again, could be the hormones.. if insurance pays, why not have them run some blood work... Also, while nothing out of the norm might appear , I think it also depends when in your cycle you do the test. e.g. could be right before your period, you may notice even more dizziness? it's worth looking into..
also, check out this link. it's from 2007... the info is still good...
http://outsidetheboxblog.wordpress.com/2007/04/16/the-hor...
I wish you all the best..