my iPhone 6 looks cloudy

okay so yesterday I was in my friends room and she was downstairs and I went to the bathroom so I put my phone on her bed and when I came out to get it again I turned it on and the top left side of the screen appeared almost looking foggy like (I'll try to see if I can post a picture of it) but I am very confused about what could of happened to it because it wasn't touched. also when I press or put pressure on that area my whole screen turns totally black and when I release pressure it turns back to the screen. I am very confused and dont know if It is a screen problem or my phone in general problem. please help. thank you!