We all have had flue and common cold. In some cases, bacterial infection occurs secondary to flue and cause throat, nose and sinuses infection. Throat infection (Glossitis and tonsillitis) are characterised by sore throat, hoarsness of voice, difficult/painfull swallowing and pain in the ear (otalgia). So ever wondered why do you feel pain in your ears or the annoying sense of fullness in your ears during these flue attacks? Here is why:
1- Our ears are connected to the throat (nasopharynx) by the Eustachian tube. It's responsible for discharge of mucus from the middle ear and equalisation of the middle ear pressure and atmospheric pressure by allowing air in and out.
It'snormally closed in rest and opens during yawing and mastication. That's why you feel pain in your ears during flying as the tube gets obstructed and you need to masticate to open it (gums, of course).
By the same mechanism, infection causes swelling in your throat or tonsils blocking this tube. So the negative pressure inside the middle ear causes the drum to retract, causing pain and sense of fullness and mild deafness.
If infection spreads from the throat to the middle ear, it causes infection in the middle ear (otitis media) which is a bad experience by the way! Mucus accumulates in the middle ear and the Eustachian tube gets blocked (by edema and congestion in it's wall due to infection). This excess mucus fills the middle ear cavity and pushes the drum causing it to bulge (which is painfull, of course) and even perforate in very severe cases and low resistance (not common).
2-The second cause may be what is called "referred pain". The infection is in your throat so why do you feel pain in or around your ears? It's referred pain. The most famous example for it is (angina pictoris) or heart attacks.
People having heart attacks feel the pain in the neck,shoulder and left arm. The cause of referred pain is not known yet but there are some theories to explain it.
The simplest way to explain one of them is that nerves have many branches that supply different areas.
So one nerver supplies a specific area in the body. Pain arising from one branch can travel along the main nerve and be felt (received) by the brain as it's coming from anoter adjacent area (projected to another area supplied by another branch of the same main nerve). In our case the 9th (glossopharyngeal) nerve is the one responsible fo the pain referred from the throat to the ear.