I've read of this happening in some anxiety books. It's a symptom of anxiety. You need to continue putting one foot in front of the other when it happens. Use positive self talk. Hopefully you carry a water bottle and can keep yourself hydrated. Keep your focus on the surroundings and maybe think about what you're making for dinner or what's on t.v. that night.
When your fear of this symptom goes away, the symptom will go away, too. Maybe you can also print up some of these replies and carry them with you. When you get that strange feeling, pull out the replies and remind yourself you're not alone. Take care!
Generalized Anxiety Disorder
60 mg. Prozac, Ativan as needed.
"The part can never be well unless the whole is well." Plato