Experiencing Random Dizzy Spells?!

Hi all,
So I have been experiencing some dizzy spells here and there, and it has been going on for a while now. It used to happen only when I stayed up late reading, or on the computer, so I assumed it was just that I needed to go to sleep. However, now it is happening more and more. It happens when I'm reading still, but it also happens at school and I haven't been able to link it just to reading/writing. It also happens when I'm walking, and today I actually felt myself swaying and even caught myself tipping over while standing still. I have tried to do my own research on it, but I have found no success, because I'm seeing so many different possibilities. Anything from exhaustion to tumors. Since this has been going on for over a year now, I'm feeling pretty confident that it is NOT a tumor. However I would just like to know if it is something I should see my doctor about? Thanks!