Purple/off color of screen center

My iPhone fell to the floor. The screen is fine, everything works..except...

After a short time certain colors are washed out. Like Facebook has a yellowish green hue to it. A white background will show a purple cloud in the middle.

It seems to change shape and vary as I use it. Then sometimes it'll be ok and then not.

I opened it up, checked all the connections, no avail.

Thank you in advance!

So1oM