Suggest Treatment For Nasopharyngeal Crusting

I am a 31 yr old female, 5'9", 140lbs. I continue to get a nasopharyngeal crusting. I've a couple sinus CTs both came back normal. I recently had an MRI to check for a Tornwaldt's cyst and this came back normal as well. I had my adenoids removed 1 yr ago thinking that maybe the tissue was chronically infected, but still i keep getting the crusting. I've been on antibiotics to get rid of the infections and it always comes back. Using Bactroban and Sinus Rinse daily helps the most, but this crusting never goes away.