Why Does One Have A High Blood Pressure Post A Brain Surgery?

Hi! my bloodpressure this last 3 weeks were very high. I was at the biokenitics and they took 2 weeks ago and the first bloodpressure was 176 over 86. The next morning, I went to the pharmacy and it was 140 over 86. The second time, last Wednesday, it was 132 over 64. But I took it now and again it was 172 over 82 and 5 minutes later it was 143 over 93. The last 3 months I 'm also very tense when I'm driving. Is this a bloodpressure problem maybe? Ten years ago I had a Brain surgery for epilepsy, but I never had a Epilepsy after that brain surgery again. I'm also not drinking any medicine now. What can I do?