What Does Absence Of Periods, Headaches And Frequent Nausea Indicate?

I ve not had a menstruatel cycle since December 23rd, I was on birth control(pill) and I m on 100 milligrams topamax twice a day for seizures. I randomly throw up, sometimes in the morning, sometimes in the evening after smoking a cigarette and coughing a lot. I ve had a cold off/on and get frequent headaches and had one spell of being really dizzy after bending down. What could be wrong with me?