Thanks for posting your query.
With the available described symptoms, there appears to be high possibility of migraine
Presence of headache, dizziness
and light headed suggests the diagnosis.
Migraine is also commonly associated with vertigo
and treatment of migraine also cures vertigo.
You should consult with internal medicine specialist/ neurologist
and should go for thorough neurological check up.
She should take antimigrainous medicines both for headache and for prophylaxis.
She should avoid tea, coffee and chocolates.
As such there appears to be no relation between headache and low potassium level.
Dr. Mayank Bhargava