High BP 150/100. It not be regulated?.

I have been taking medicine for high BP from past 10 years. The medicine has been changed thrice. It started with AMODEP AT ( 1-0-0) 10 years back. BP was regulated. It was changed to AMLOVAZ 5 mg (1-0-0) three years back. I cuased swelling in legs and was changed to LOSAKIND 50 mg (1-0-0) in April 2013. Again it was regulated for all thee years. In July 2016 Dr. noticed variation in BP occasionally recording 150/95. Advised 1 additional tablet in evening (1-0-1) . Took for few days and then it was normal 130/85. But from tow days again 150/100. Doctor advised change to TETAN BETA 25 Mg (1-0-0) . Reason given was body demands different medicine after some time as it gets immune to any medicine used continuously. Hence LOSAKIND was changed to TETAN. I am concerned as I am not sure whether this true. Is this the real reason for change of medicine. Higher BP could also be due to tensions in job or daily life and also variation in diet ( Salt intake). Can it not be regulated ?.