i am experiancing a very sharp pain in my left side -top of head torward the rear-it feels like i hit my head or possibly pulled a mussel- iwas carrying alot of milf and stuff in my left hand last week and i thought i sprained something -went to the er and they did a catscan and could not find anything and said maybe it is a pinched nerve or mussel- what would cause my head to hurt- any ideals-w.s.