I have never had dizzy spells to the extent that you describe, but I can tell you that you should seek a second opinion. I had severe itching when I was pregnant and the Dr. said its "normal" and dismissed it. Eventually I sought a second opinion and insisted that they run tests. They did and I had a dangerous condition which we eventually treated and all worked out OK. But needless to say, it would not have been OK if I didnt get the help when I did. See another Dr., insist on tests to be sure. You know better than your Dr. if you are not feeling right. Trust you instinct - even if this is your first pregnancy. Hopefully everything is fine, but make sure it is until you feel comfortable. Do just what you are doing... research. Look on the web, see if other mothers have had this then take what you learn back to your doctor, or another! Good luck and many blessings.
K..