Dull Ache behind my left eye

I have this headache that shows up about every month or so.  It's always behind my left eye.  It can last a few hours to a day or two or three.  If I don't take anything it can eventually turn my stomach to the point I have to go home because I don't feel well.   Is this a migrane (migraine)?  It's not a sharp pain, my vision doesn't change, it's just this dull ache with pressure behind my left eye.  

[Ray T Oyakawa, MD]

There are many causes from glasses to things more serious.  You should see an ophthalmologist.

Dr. O.

[yarrow]

As Dr. O says, you should definitely see an opthalmologist.  And while you're waiting for your appointment, check out migraines:

http://adam.about.net/reports/Migraine-headaches.htm

Note:  Do not try to self-diagnose, but definitely ask questions of the doctor when you see him.