Headaches and brain , vascular , or nervous system causes

The symptoms you reported (headache that awakened you, losing balance when standing) are not specific enough for a definitive diagnosis to be given. The symptoms might be related to high blood pressure, temporary insufficient blood supply in the brain (transitory ischemic attack) or by a migraine.
All three conditions have different causes and slightly different accompanying symptoms. For example, a migraine can be accompanied with sensations of pins and needles in the face, hands or arms. It might be announced with visual sensations that create the so-called aura.
On the other hand, a transitory ischemic attack might turn into a more serious condition such as a cerebral infarction. This happens when the blood supply is reduced more than in a transitory ischemic attack and the brain tissue is more or less damaged. The accompanying symptoms would depend on the affected brain area.

You might want to visit your family doctor for a physical examination and measurement of the blood pressure. You might be referred to a neurologist for examination of the neural system. If nothing serious is detected, the doctor might define the cause as a migraine. Since the causes for a migraine are not very clear yet, you might be recommended analgesics to reduce the pain. You might be advised to check for the specific symptoms that create the aura and thus try to prevent or ease the headache.