My 2009 MacBook Pro has started flickering pink in white areas

I have a 2009 MacBook Pro 15" screen. Just today it has started flickering pink in certain areas of the screen. It has happened on and off all day. I tried to take a screen shot, but it didn't show up so I took a pic with my phone. It's a little hard to tell in the picture, but the pink area is flickering in and out.