I'm sorry to hear that. Have you asked before? When I am in the pharmacy, we take it anywhere between 5 to 8 minutes apart. The problem with blood pressure readings, is that when it is one reading it is an "isolated" reading out of continuous fluctuation. Doctors are already writing that Rx for hypertension based on one isolated reading. This is another reason why I am getting the 24 hour BP monitor belt to wear at night to get a reasonable baseline before going ahead with prescriptions. Much of this I have read, including the Mayo site, among others.
In my opinion, based on close friends and relatives, one thing leads to another and they are in "polypharmacy," in which they suffer from so many side effects treated by other drugs that a physician doesn't have a clue about what's wrong. The symptoms are buffered by side effects. It is my personal goal to be on as few meds as possible.
I hope there will be a clear answer to the dizziness. I hope you can get a baseline. I validate your doubts.

I think that is because the doctor knows that he would get three slightly different but similar readings. So what would the benefit be?