Why is the color of my screen changing

I had my tab s for about 2-3 years now and I only lightly dropped it twice. The first time was a week or so after I got the tablet and it worked absolutely fine until i dropped it again a month ago. For the couple of weeks, my screen's been flickering and each time it comes back it's either really bright (the brightness setting has changed it is as i left it) or it's normal lighting. I've already did a factory reset on the tablet but the problem is still there and now it's flickering and then going black everytime I use the touch screen.