According to WebMD, pain from an ear infection typically persists a matter of hours, although it can continue sporadically for several days. The fever usually lasts a few days. While the immune system is strong enough to fight an ear infection, antibiotics may expedite the process.
WebMD says that, in severe cases, fluid may build up to high enough levels of pressure to cause the eardrum to rupture. This process actually helps drain the fluid and reduces pain and fever, clearing the infection. The eardrum can heal itself within a couple of weeks. Fluid buildup may last longer, sometimes months before it drains completely.