having very unusual head pain that only lasts for a few seconds, same localized spot every time, back of head , above neck (base of skull), only in a zone about the size of a golf ball--pain does not radiate outwards, just in that one spot but so intense that (for only a second or 2) that it takes my breath away & stops me dead in my tracks. No tingling in arms or legs, no pain anywhere else. Have noticed a massive & rapid decline in vision but no other pain anywhere else.