No you are not crazy. This is the same exact "floating" feeling I complained about for YEARS! A low dose Ativan helped me a lot. (.05 mg). My Neuro suggested it and said she had a lot of her M.S.ers complain about this feeling and the low dose Ativan helped.
At first I thought she was blowing me off as some type of anxiety (which it will cause you to feel as well as phobia as you may become afraid of it). However; the ativan for a couple of days seems to break the cycle of the feeling. Hope your doc will agree and let you try it. I don't take it everyday....just when I feel I am having a hard time. When I get the floating feeling....I can't drive. The ativan has given me back my driving.

I know the feeling is not debilitating, but disturbing and makes you feel like you are crazy. Bless you for posting your concern because many of us feel "nuts" and its comforting to share common experiences.