What Causes Dizziness When Under Treatment For Hypertension?

I am having high bp and under treatment. I am taking olmesar a tab one o. d.and autrin75 one o d since about 2yrs. Recently i vsited my native.one day traveling-2days marriage function-one day return journey.iam doing night work.after retuning i stareted giddiness and not able to do night work.i started vertin16 1tds.my bp is about90/130. Pl let me have your advise.