What Causes Facial Pressure Post Long Time Usage Of Decongestant Tablets?

I've been scuba diving almost daily for the past year. I was eating three decongestant tablets daily and snorting lots of salty water because I've had a reverse block before. I have stopped eating decongestant tablets and now my sinuses are always squeaking and I can feel the pressure inside my face. I've also had a very blocked noses for about two weeks. Is this a side affect from eating too many tablets?