What Causes Persistent Headache?

i had a persistent headache for about 2days and checked my bp at diferent times and was 180/76 and 150/84 when i got to the hospital it was 145/74.Dr gave me ramipril 5mgdaily but i feel that d dosage is too much but the Dr said it means i am hypertensive. does it mean that because of this blood pressure i am hypertensive? moreova i dont feel realy good