I've have headaches i've never had before and get dizzy when i stand up. i drink plenty of water and have normal blood pressure. what could this be?

Head Ache: Most head headaches are due to tension. But if they are associated , with dizziness or nausea or vomiting or blurred vision it could be more serious & will need further evaluation. If you need further info , will be glad to discuss it in detail

Orthostatic hypotens: In spite of normal blood pressure patients may have orthostatic hypotension due to medications use, or as a complication of neurological conditions. Depletion of salt is most common reason. Using support stockings may improv symptoms, but office evaluation is usually required.