What is causing frequent headaches in the middle of skull?

Hi doctor,

I have had the headache issue for over 12 years, which seems to worsen. The onset of this headache starts with pressure getting built up in my head, like stress for no reason, and all of a sudden, the headache begins at the back of the head, and within minutes it gets severe. If I have to describe the location, it is above the base of the skull and below the top. The pain is so intense that I have to take a pain killer else it will not subside. There are no other symptoms like vomiting, dizziness, nausea, and speech imbalance. The pain is pulsating or throbbing, increasing with any movement or applying pressure. This headache also comes on while having alcohol and, on a rare occasion, during ejaculation while having sex with my partner (once in a blue moon scenario). My cervical spine CT (computed tomography) scan was done, and the reports were normal. The onset of a headache has to do something with time as well. It also gets triggered sometimes when I wash dishes or cook food requiring focus. I do not know the pattern, but all I know is it is ruining my quality of life. These frequent headaches and consuming painkillers have started affecting my digestive system. I want to get rid of this problem. Please suggest.

Thanks.