I have been dizzy on and off for three years now, and my doctor just says its viruses since my thyroid cancer. what do you think?

Vertigo/Dizzyness: One important distinction is to determine if you have dizzyness versus vertigo. Does the room feel like it spins around you? A physician also needs to evaluate your nervous and cardiovascular systems, and any sensitivity you have to thyroxine and your sugar levels (endocrine system). A physical exam and blood tests are indicated. Orthostatic bp measurement also a good idea. Good luck.