As you knew the Fluticasone component of Advair is an anti-inflammatory drug. It is possible that for 7 years you had non-infectious inflammation of your throat, suppressed by the inhaled steroid and is now active (in effect, unmasked) . The most common causes of such a sore throat would be chronic post-nasal drip and Gastroesophageal Reflux Disease (GERD). You might want to ask your doctors to check out these possibilities.
Good luck
I also had a mri of the sinuses which was normal. And a ph testing for reflux which was normal.