Feeling dizzy when changing your head position (lie down from an upright position, turn over in bed or sit up in the morning), with lightheadedness, imbalance when walking, and nausea, could be symptoms of Benign Paroxysmal Positional Vertigo (rarely serious condition that is self-limiting)
You may noticed that moving your head to look up or look down, also, brings the same symptoms.
Symptoms like dizziness, nausea and headaches, could be symptoms of hypertension, but typically don't occur until high blood pressure has reached an advanced stage (a few people with early-stage high blood pressure may have these symptoms).
If your headache is a piercing, throbbing, or electric-shock-like chronic pain in the upper neck, that spreads to the back of the head, and behind the ears, usually on one side of the head, it could be a occipital neuralgia.
You may also check the idiopathic stabbing headache, if you feel headaches as a stab from an icepick, nail, or needle and typically lasting from a fraction of a second (always felt at the same spot).
Best wishes!
Marija