I have been taking Effexor for a year after my GP became concerne...

I have been taking Effexor for a year after my GP became concerned that Serzone was causing liver damage. I haven't had any side effects except when I stopped taking it for only one day, I started to get a little dizzy. OK. I DIDN'T miss a dose this time and right now I am so dizzy and nauseous I actually broke a cardinal rule and went all blubbery on my husband. Talked to my doc about this last week and she said dizziness could be caused by menopause. NOT LIKE THIS!! I am almost afraid I have a brain tumor or something. How can I start to have these effects after a year? I am experiencing the brain shocks--when I turn my head it sounds like someone is rapidly shaking one of those plastic film canisters of rice by my ear. I also have light flashes in dark rooms (like at night). Is this Effexor?