This has happened to me 4-5 times now.. it's a really bad shooting pain at the back of my head and occurs on the build up and after ejaculating and lasts for 15 to 30 mins.. i havent yet seen a doctor but has anyone suffered from it and knows what it could be
You say 4-5 times but over how many days?
Do you generally get headaches at other times (some people don't)?
Do you notice any other symptoms at all? Is your vision ok during that time? Is the headache accompanied by nausea?
How far down the back of your head? Does the pain go down the back or side of your neck or is it limited to the back of your head? Many headaches are caused by neck and shoulder muscle and nerve issues.
Are you regularly urinating? Like the others have said, increase your hydration, drink sports drinks and see if that helps.
You say it occurs on the buildup and that is the time when everyone's brain is not getting as much oxygen/blood (hence the orgasm term, "the little death" but obviously it should not be painful so I would think that if this has come on suddenly and continued over a period of more than a week that a doctor visit is in order. The doctor will want to know other stuff like how much caffeine do you consume each day, do you smoke, etc., because those affect the brain's blood vessels.
Let us know how it all turns out!