I've had vertigo on and off for a large part of my life.
Once they told me it was a middle-ear problem, and that I might try cutting back my salt intake. I tried it and it worked!
Then I developed ear infections that wouldn't go away. Antibiotics didn't help. I took Vitamin C in high doses AND gave up milk and ice cream - poof! Ear infections went away, so did the dizziness they caused. I also gave up drinking fruit juice and any cold beverages. I drink filtered tap water, no ice. Cold stuff isn't good for your sinuses, and can cause edema and dizziness.
I know that blood pressure medication can cause vertigo. I tried Lisonopril for my kidneys (my blood pressure is actually quite low) and it made me feel lousy. I had to quit taking it, although it didn't make me dizzy - just tired and depressed.