It is possible that you could have a problem with your inner ear or your sinuses. There could also be a blood pressure problem. If the dizziness continues, I suggest you tell your doctor at your next visit.
I am sorry that you are having trouble with dizzy spells. That can be very difficult to over come. Yes I have them but not like you are discribing. I usually for me means inner ear infection, sinus problems again, low blood pressure, and/or low sugar. Well these are thoughts hope it helps but i would for sure make an appointment with my doctor soon.
Best Wishes for the reason why,