Sinus pain behind the ear is a sign of sinusitis, according to the Mayo Clinic. Sinusitis is an infection that can be acute or chronic.
Acute sinusitis is a temporary condition that typically resolves on its own. Along with ear pain and pressure, it can cause facial pain, a reduced sense of smell and nasal obstruction. Mayo Clinic notes that chronic sinusitis lasts longer than acute sinusitis, and it can cause many of the same symptoms. People should talk to their doctors if they suspect they have sinusitis and if it doesn't get better with time. If they have difficulty breathing, they should seek medical help immediately.