While I cannot diagnose, it sounds as though you may be describing thrush.  The  use of corticosteroids in the oral cavity can diminish normal bacteria that live in your mouth and throat and create an environment that favors yeast.  This in turn can cause a yeast infection called thrush.  Thrush usually looks like small white specks.  It may or may not be irritating.  This is not uncommon and should not be a reason to quit taking your Flovent.  There is an easy and effective cure.  The best thing for you to do is call your doctor and describe your symptoms. 

Like you I take Flovent and rinse like a good boy, but I still get thrush every once in a while.  My doctor usually prescribes a pill that I take for five days with great results.