Good morning. My name is Dani. It is very nice to meet you. I am sorry you have to worry about thyroid problems. I too get "dizzyness"..sort of, more like fainting and fainting with jerking (convulsions). I have hypoparathyroidism.
I think a good place to start would be to go to your general doctor and tell him/her your worries, but be sure to mention the family history. He/she may do blood tests then send you to an endocrinologist. Reguardless of the outcome, I want to send you a very warm welcome. I hope the doctors are able to pin point the cause of your symptoms as quickly as possible.