I've got menieres and get a lot of vertigo and such and have flown quite a few times over the past few years and been ok, mostly short flights eg Budapest, Amsterdam, Prague, Milan... but did 7 hours each way to New York and was still ok.
I take stemetil and betahistine daily.
My ex's mum has really bad labryrinthitis and has done for a while and even though she was bad when we went to Cork for a hen do, she was fine flying as well.
I can understand the fear, my mum was funny about the thought of flying as she has menieres too and my brother gets married in Canada in September.
Obviously you have the same chance of being affected by it as normal but it won't be made worse by flying from my experience.