Hi i was reading your message it sounds to me like its your blood pressure goin to your brain my friend gets headaches like that but hers are off the chart bad...... ive had two brain surgeries and the headaches i was gettin when they found my tumors were really bad the shot down the back of my neck.. u may also be in the early stages it really doesnt sound to me like tumors how ever id really get a cat scan or mri done with contrast ... the contrast shows where the blood flow is so u should recommend that ... also id get a real good docter and if it does happen to be tumors ... hope and pray that its not... I go to Johns Hopkins in Baltimore MD i have one of the best nerosurgeons in the world its worth the time and effort to seek him out ... if you do find out that u have tumors .. i have reocurring meningiomas they grow on the surface of my brain i have another one so im waiting till july for my next mri and see where to go from there...
As well, my cousin has/had a cancerous tumor and never got a headache so... headache is a general symptom and can be linked to a lot of things from migraines to BP (like countrygirl said!) to hormones to anxiety to sinus to caffeine withdrawal to allergies to... in other words your PCP has to rule out the common causes and then get on to the rare stuff like brain tumors.
I hope you have an intelligent PCP that will determine if one of the commoner causes is at fault. Only then if many or most of those are ruled out would I seek out a really good doc like CG suggested.
Oops meant to address that last one to Blutz!