Three doctors have told me that my dizziness is due to anxiety and bio chemical reactions. i am terrified it is a brain tumour, how can they be sure?

Trust Your Doctors: I will assume that you have been evaluated by all three of your doctors. Depending upon their specialties, each may have examined you from a different perspective and ordered different studies and tests. Finally they all collaborated and determined the dizziness is due to anxiety and not a brain tumor. If you are still uncertain about their findings meet with them again and share your concerns.