is a sense of spinning that occurs because of an abnormality in the inner ear or between the inner ear and the brain. It produces the sensation that your head is moving when it really isn't. It is often accompanied by the sensation of nausea which can be the worse part. The most common cause of vertigo is an entity known as benign positional vertigo. This syndrome results in vertigo that is initiated by head position often when someone turns quickly. There are many other causes of vertigo that I can't go into here.
While it's difficult to tell from your short description, my gut feeling is that you are not experiencing vertigo. A strange feeling in your head that occurs when you stand from a sitting position is often due to blood falling from your head because of gravity. We call these orthostatic symptoms. They can be caused by dehydration, blood pressure medication, and problems with your heart.
I suggest that you schedule an appointment with your primary care physician
. He or she can take a more detailed history of your symptoms and perform tests in the office to figure out if this is vertigo or orthostatic symptoms. Once that is determined, then you can then undergo testing to find out why you are having these symptoms. Good luck.