A persistent, recurring headache that doesn't respond to migraine tabs might possibly be sinus related. Have you had a recent run of colds lately? Is your environment damp (marshy, rivers, low lying etc.)? Other symptoms are: unexplained toothache, a feeling of having been smacked in the face (honestly), watery eyes, runny nose, general "fluey" stuff. I' go and get it checked out if I were you.