Head Pain On Standing Up, Sitting Down, Short Episodes, No Blurred Vision. Causes And Treatment?

2 days ago i woke up and when i stood up, my head hurt. It only hurt for like a minute, i took a couple of steps and it stopped. Now, this has been happening every time i sit down. When i sit down, then stand up my head hurts for a couple of seconds and goes away. I went to a family doctor and my blood pressure is fine. She said for me to drink more fluids and no alcohol. So i have been, nothing has changed. It is mainly MY right side of my head. More towards the back. I havent had any blurred vision and really havent been dizzy.