I need desperate help with my screen!

My iPhone 4S is a little battered and is quite smashed, but is still working near enough perfectly, maybe a little slow. But today the screen went crazy, the colours look inverted (but it hasn't been inverted through the settings). Things I go on stay on the screen and take a while to fade away.

In the photo, that page of my phone only has one folder (the one in the top corner), yet the image of my other apps from the page before are still there after I had swiped across. PLEASE HELP!!