My iPhone 6 has large black spots/dots on the screen. Help?!?

A while ago I noticed a black blob on my screen. It went away a few days later. Recently I dropped and cracked my phone. Now about 5 days later appeared multiple large black blobs/spots/dots on my screen. in addition to being black they have hints of green & red. its really freaky looking. Is it sone thing that can be repaired/replaced or do I have to buy a complete new phone?