This isn't anything like you have, but in the late 80's and early 90's, shore diving with heavy gear in the PNW, I sometimes crawled out onto the beach with a pounding headache. I would just dump my BCD and lay on the beach until it subsided. I thought it was from sinus problems. I thought it was from the cold water. I thought it was migraines. Much later I found I had a rare tumor on an adrenal gland. The weight belt and BCD were pressing on the adrenal tumor and making it release massive amounts of adrenaline. This raised my blood pressure sky high and gave me terrible headaches. It wasn't till many years later that the headaches started to come more often, and they finally figured out why.