It's time to go see the eye doc. There are a wide variety of things that can cause your contacts to start irritating your eyes. They range from very minor to things that can potentially make you go blind if not treated.
Being someone who prefers contacts myself, I wouldn't fool around with it. Not getting this kind of stuff sorted out promptly can make it so that your eyes aren't healthy enough to wear contact lenses again for a very, very long time.