Also gently rotating your fingertips across your brow bone is worth a whirl......

Try the eyebrows from the centre out - if it is sinus and the fog today is a good clue, it works for a few minutes. If it is in the back of the neck - its tension. Eyebrows and eyes - it is sinus. On top of the head it may be cold weather - migraines are the capilliaries shutting down and cold weather does it - though it will have done it before and today is not the coldest recently.