I guess you are late into the game and controls a large part of the map since that is the only time I have had such problems...

Each province which successfully revolt (or is it revolts only) will start of more revolts....

Where is your king placed...one thing which cause more trouble then any other is a king fighting in a far of land...always always have him in the centre of your kingdom...

Are you building up your provinces because otherwise they wont be content...it will give your king the nice builder virtues...

If you play by glorious archivments a tip could be to skip the revolting provinces since you do not need every province to win...just enough of them...otherwise battle on and may victory grace your blade...