Light headed & dizzy

I've had high Bp the past two months & woke up with a pounding headache & bloody nose then Today at work I got very lightheaded/dizzy & turned pale white & clammy like I was about to pass out. I called my dr & after phone tag with the nurse she basically told me it was a normal pregnancy symptom & unless I pass out I shouldn't worry I told her I felt slightly crampy & had a backache once the symptoms passed too & still the same response... I don't feel convinced, has anyone else experienced this? (Im just over 18 weeks with my first pregnancy)