I had quite a lot of blood work done in early August, although this (dizziness) has happened since then. I guess I'll just see how things go. Drinking water is a good suggestion, also. I seem to require a lot, and start in the morning with a glass or 2 of water, then move onto green tea with mint.
I used to have very low blood pressure, but actually it was a tad bit high when I went for my physical in August. I maybe should have it tested again.
Pre-fibro, every few years like you, I get an intense "room spinning" dizzy spell. One time, I was driving and had to pull over for about 5-10 minutes till it eased up. Knock on wood I have not had one in awhile.
I do have low blood pressure like some of the others and a resting heart rate of 80 also. Thanks "ginny" that was interesting to hear about fibro.
It could also be an inner ear disorder. I have one, and I often have vertigo and/or feel off balance.