Why is my screen green?

I was texting a friend today and all of the sudden the entire display turned green and with some distortion lines at the top of the display that seem to come a go as I apply pressure. Everything works on the phone minus only seeing green. No issue with sound, touch, auto dim, or brightness settings. Everything is working as it should minus the display. Is there a fix that doesn't require a whole screen replacement, and if not will that resolve the issue? Also, what caused this to happen in the first place?