I believe this is what i am experiencing:
Recent observations by Doug McGuff, MD suggest that EIH may be caused by stretching of the dura mater (outermost of the three membranes covering the brain and spinal cord) as a result of increased BP in the cerebral veins caused by retrograde venous flow towards the brain. The onset of EIH is usually experienced during intense exercises for the legs, hips, and trunk, during which there is a large amount of venous congestion in the pelvis and abdomen. In an article entitled The Mystery of Exercise Induced Headache, in Vol. 5, Issue 3 of The Super Slow Exercise Standard, Dr. McGuff writes,
"This congestion is a result of soft tissue compression, Val Salva and
massive venous return from the legs stimulated by intense muscular
contraction. This massive venous congestion can create a strong
enough force to drive venous flow in a cephalad direction (towards
the head). Perhaps, in some subjects, the force is great enough to
reverse the gradient of cerebral venous drainage so that venous blood
is pushed up through the jugular veins into the confluence of sinuses...
...Theoretically, a threshold level of venodilation and pressure
transmission would have to occur before the dura could be
stimulated. Once this threshold is reached, look out! Dural stimulation
produces severe, sudden onset pain that can persist for days."
I do not usually take any type of caffiene and I think that the combination of working out and the elevated blook pressure from the caffiene could be causing this headache. It is very severe pain and trying to work through it is impossible. I would have fainted if I did.