Whats wrong with my eye?

In january or so my left eye started getting red in the inside corner. I didn't think much of it. Then I woke up one morning with all the slimy, crusty puss that you get when you have pink eye and my eye was ll pink, too. My mom took me out of school to get it checked but when she looked at it in the car, it was all clear, so we didn't go. The pink eye never came back, but now its permanently red in that corner and it won't ever go away since then. Sometimes the redness gets lighter when the rest of my eye is clear, but at night when I'm tired, it becomes even darker. Any suggestions as to what it might be!?