Why is my Samsung galaxy s4 phone screen turning green and black?

[AC Question]

About 4 hours ago, my Samsung Galaxy S4 fell off my kitchen counter, landing on the bottom left hand side. At first there was no visible effect on the phone, the phone has been dropped many times, and is cracked quite severely. Anyways, so I look at my phone about half an hour after it happens and there is a small green dot (bruise like) on the corner of the screen. Didn't think much of it, but it is growing very large, and transforming into different colors, help?

 

[B. Diddy]

Welcome to Android Central! The screen is most likely damaged, and that defect will probably spread to the whole screen. Back up or sync all of your important data now, and take it to a repair shop to replace the screen.