MACBOOK AIR SCREEN APPEARS FADED WHITE WITH WHITE AND GRAY LINES FLASHING

I am using a Macbook air 13” Early 2015 model and for less than 3 years it works completely just fine. Until last July 31st, I only used it for 10 minutes after a 5-day hiatus (I think) of hectic work. Suddenly, a fine horizontal lines of white and gray appear randomly in my screen and the problem kept on getting worse until every text and graphics becomes distortedly unrecognisable. I panicked and turned my computer off. When I turn it on, same problems appear.

I tried the NVRAM reset that I’ve read here and by pressing option+command+p+r simultaneously for 20 seconds, I’ve heard the reset sound and release the keys. It went well. It went back to normal and for precautionary measures, I have decided to give my computer a break.

Today, I opened my Mac Air and while browsing, small portion of the screen began flashing the lines again. It flickers white and black lines until the screen faded to black. I tried the NVRAM reset again, it didn’t work at all.

I am currently connecting it with my monitor and the picture below shows that in the monitor, my laptop works just fine. I updated my OS using this setup and when It completed, the screen flickers have lessened but from time to time, still covers most of the screen (see picture below). Is this a defect on the display screen?

Can anyone pls. share something about how I troubleshoot this one? My school begins on Monday and this is a nightmare for me! Please.

Your input will be much appreciated!