Can acute sinusitis cause ear pain?

Yes: Acute sinusitis by causing inflammation in the nose and nasal cavity can secondarily cause swelling in the eustachian tube. This eustachian tube swelling can create negative pressure in the middle ear and lead to ear pain.

Yes: The inflammatory pus that drains out of the sinuses will go past the drain openings (eustachian tubes) of the ears on the way down the back of the throat. This can cause those drain openings to swell shut, creating negative pressure in the middle ear. This can be painful.