I have seen quite a few posts from people with both sinus and ear issues after chemo and herceptin. My wife also experienced some dizziness/vertigo that was blamed on an inner ear infection and she had recurrent sinus infections. The doc said the two could have been related. Have you read the posts about herceptin side effects?
http://www.her2support.org/vbulletin...t=side+effects
Hope I got the link right!!