Hypertension. Always been high. with!

I am being diagnosed of hypertension however I strongly believe it is not true. Because of how I feel when I get to the hospital and they are about to check my BP. From 2015 when I was first told my blood pressure was high, from then each time I went to the hospital it has always been high. With regards to how I feel, as soon as I am in the hospital, I suddenly feel my heart beating fast and I get headache. Slightest mention of my name, say ,to see the doctor or to come for medicine makes my heart skip a beat. But as soon as I leave the hospital I feel ok and normal. Its been like that for the past three years. Because of that even when I go to a pharmacy to check my bp, I'm with fear.i did an ambulatory bp just September and the results said I was below the threshold for hypertension. My ECG was normal too. For the past few days I was feeling pains in my arm and so went to the hospital  and when they checked my bp, it was high but I had the same feeling. Now they say am hypertensive.