I have been getting wierd neck popping and shocklike pains right up into the head and headaches 90% of the time for 3 years. I would get the pain from both eyeballs to my inner ears and to both sides of the jaw. I though I was having a stroke or something. I have had xrays, catscans, mris and all showed negative. I found it is related to the uppper muscles in the neck "sub occipitals" locking up in a flexed position due to scar tissue. in turn these muscles block off arteries to the brain and irritate nerves. smoking mj only made the pain worse also and it felt like fluid shifting in the brain and cold sensations on the head a lot. but I have found my rellief with shrooms, and peruvian torch cactus combined with stretching exercises for the neck.