Cold phone with lines??

So yesterday I dropped my iPhone 6 in the snow while walking my dogs and I got home when I realized that I didn't have it. I found it brought it home it miraculously was fine aside from being cold. I went several hours without having any issues but then I went out for a second walk. The phone died of cold, which is normal for my phone I got back inside and with it still being dead I dropped it accidentally which is a tumble it has taken many times, I have a great case so I wasn't worried about it. When I plugged the phone back in the white apple screen showed up but the screen is not half black with rainbow vertical stripes and also white stripes that give it a white hue. The stripe placement and color also change while I'm using it. The screen and touch work fine but what is it?? Do I need to get it fixed? I've tried restarting it and I left it for the night. I'm praying I don't have to get it fixed so if anyone has any ideas PLEASE HELP...???!!