WHAt Med for High blood pressure

I have tried telmastartan 40 mg doesn't really seem to do the job. Linispril did ok job at 30 mg. Without knowing why my blood pressure is high. How would I know if a diretic or amlodipine would work. I am getting frustrated with this High blood pressure thing. I tried supplements like Nitic oxide from Berkely and magnesium turate throughout the day 3 to 4 times. Nothing seems to work