black spots on my phone

[chy]

I cracked the bottom of my phone one day and when I checked it, it wasn't cracked or damage at all. Now for some reason the cracked part of my phone has expanded and now my screen has a little crack in it. One day before I was to leave, my phone has started to develop black spots on my screen and they seeem to expand if I'm not using it, or sometimes my phone gets hot and the black spots expand. I don't know where this came from, but has anyone experienced this?