It could be an "Aura" indicating the start of a migraine. (similar to the Aura epilepsy sufferers feel before the onset of a fit). I get an aura with my migraine - but not all the time. It is only when going to be a major migraine. Mine is wee marching dots (look like wee ants
) and they march 4 wide in a backwards C shape.
Might be worth keeping note of when you get it, and if sore head etc follows it. Oh and STOP GOOGLING SYMPTOMS!
Hope you get it sorted soon chick. I know how it feels and it is not nice.