Re: Dizzy with no reason/when get up (not always)
Since you experience vertigo, rather than lightheadedness, the symptoms are unrelated to blood flow.
So it sounds like you experience vertigo when you move your head from the reclined position, to the upright position. These symptoms match those of Benign Paroxysmal Positional Vertigo (BPPV). This is the most common cause of vertigo which is caused by tiny calcium crystals that collect in one of the balance canals of the inner ear. Treatment is very simple, and the cure rate is extremely high.
Judging by your particular symptoms, it is a logical conclusion that you have BPPV of the posterior canal. This can be treated with the Epley maneuver, however you must know which ear is the symptomatic ear.
If you are uncomfortable performing an Epley maneuver at home, you can talk to your doctor, and he/she will likely refer you to a knowledgeable physical therapist.