I Have Frequent Dizzy Spells. Most Of The Time It

I have frequent dizzy spells. Most of the time it last a couple of minutes and one time lasted three hours. I have been woken up in the middle of the night twice over the past year from a loud pop in my head. I also have frequent bladder pressure, but when taken a AZO for a few days the pressure goes away. What does the symptoms means? I am concern mostly about dizzy spells as I have had several while driving.