You should consult a cardiologist
for high BP. To diagnose the cause tests like
kidney function, liver function, lipid profile, thyroid, adrenal gland function, EKG, ECHO, tread mill etc are done. If no cause is found then what you have is essential hypertension. The doctor will need to adjust the type and dose of medication. This may need a few trials before a medication that suits you is adjusted at an optimal dose. Keep a morning evening record of your blood pressure for a few days.