My IPad screen is getting weird.

My IPad screen colour has gone extremely weird. Colour are becoming somewhat a bit negative (Negative colors are off) and colors look like they are slightly fading away. It is becoming a mix of greenish and pinkish but it is not a green static screen. Didn't drop it or anything and just bought it about a year ago. Slight marks of previously used apps and keyboard also stay on the screen even after I have exited the app. It went back to normal after a while but after 4 hours, it became weird again. Anyone knows the problem?