chronic headaches

Have experienced chronic headaches over the last year.  Not sure what is causing them.  Would appreciate any feedback.
-  initally treated as a sinus infection (I have seasonal allergies).  That was not the cause.
-  got eyes tested (had old prescription but do not use them); have new progressive glasses for near sighteness and stygmatism and seeing from afar; can read without them (liek I am right now) but perhaps the stygmatism may provoke eyestrain ??
-  earn/nose/throat doctor inspected sinuses with vidoe tube, but they were clear; said the aches are cardiovascular-related ??
-  use loretadine periodically when I get a little congested; the congestion does increase the chronic head aches
-  never had chronic headaches before now; the pain is not severe
-  ache level goes up when I bend over (probably tid to blood pressure going up, I guess)
Based on these symptoms, is there a specialized doctor or test I should take to determne the cause.  Could these symptoms be an early warning for stroke conditions ?
Thanks