I have severe head throbbing that is geting worse .It occurs when I stand up or look up from reading. Now it happens just sitting still. I am getting a sound like a helicoptor propellar turning inside my head. I hold my temples because the throbbing is so severe it feels like my brain might explode. I do not suffer from anxiety or stress. Any one have a clue of why this is happening. I had my blood pressure checked and it is normal. Thank you emilia c