I'm 88. For years, I've noticed I don't walk in a very straight line. There have been a few times in my life when I've felt a little faint. I never feel faint when I'm seated. Recently, when I'm out walking, I sometimes notice a strange feeling in back of my neck. When I was much younger, a few tmes I felt a little faint, so I'd bend over with my head down and the feeling would clear up. Any cause???