Hi.. If you want a medical explanation, then here it goes.. The ear is connected to the throat by a tube referred to as eustachian tube.. The ear invaribly gets affected with persistent infections of the nose, throat resulting in collection of the fluid in the middle ear, a condition referred to as serous otitis media.. This probably would be the cause for your ear pain.. The condition may have been precipitated by your position but that is not the only factor why this happens..You would need to see a doctor if the pain persists or if you develop fever (serous otitis media can get infected if not treated adequately and may need antibiotics... Hope you have understood ...