Might be more common - but undiagnosed
This is probably more common than we realize, but most people don't get a diagnosis on it; as there could be a lot of other things going on, and you know, people put off knowing if they can ...
There is a type of headache that is a searing, 'hot poker type headache' in the back of the head & running down the neck (This is the area you are talking about?) It is one symptom of endocrine disruption from chemicals such as 2-butoxyethanol (aka ethylene glycol monobutyl ether) I suspect it to be in the area of the pituitary gland (?)
I've talked a lot about it already, so please check my other posts, and also do an internet search.
Do you have other symptoms such as fatigue, or swollen organs, such as spleen, gall bladder, thyroid, testes, heart chambers? You can't imagine all the harm this one chemical does; and then how many more chemicals are being used at work and in our communities these days, as compared to 50 years ago when many of these ailments were practically unheard of.
There is even concern for male sperm quality and reduced counts in this same time period (This particular chemical targets the testes) There were major news articles about this in 1996: New Yorker, New York Times, USA Today and Mother Jones for starters. From studies done, it appears that at the rate we are going there will be more and more families that will have difficulty in having children, and by the next 50-70 years men will have a zero sperm count.