Thanks for writing your query.
After reading your post, it seems that your headache is due to increase in blood pressure.
Increase in cholesterol
and other harmful fats result in atherosclerosis
leading to narrowing of blood vessels. This can result in increase in blood pressure.
You should continue with the medicines prescribed by your doctor.
Also get your blood pressure recorded twice daily for atleast three consequtive days.
Also avoid excessive salt and oil intake.
Since you are having blocked nose, other cause of headache can be due to sinusitis
Steam inhalation can be helpful in decreasing the symptom.
If the problem persists, get yourself clinically examined.
I hope this is helpful to you.