You need to see a doctor or an optician soon.
One of my friend often forgot to get contact lenses out and ended up losing the sight in one eye through infection. It may not be that serious, but you should pay much attention to it.
Do you get other symptoms? If you only get cloudy vision, you can wait for a few hours to see whether it will go away or not. If you still have cloudy vision then, you should see your optomitrist as quickly as possible and just explain your problem to your doctor.