Woke up in middle of night after taking first day, 2 pills; the room was spinning, I was nauseated, tried to get up from bed, had to hang on for balance as I went to restroom. When I got up that morning, I had to hold on to walls, etc. for balance. Thought I may have had a stroke. Felt weak rest of day, but balance seems to be back (third day) Is this common? Have taken Zithromax in past with no problems..Is there something different in the generic??