I recently encountered a similar case, my phone suddenly shows green screen and one day, it just decides to go BLANK. The screen no longer works, but the phone still works perfectly. I would say that your screen is almost BUSTED. But no worries, as long as there are no internal hardware issue on the motherboard. You can replace the screen then you're all set.

What I would recommend you to do first is to backup your data ASAP before you cannot access your phone's screen. It would be great if you know someone or a store that can replace the screen for you. Taking it directly to Samsung will be expensive, and at that point, you might as well, change a new phone. One word of advise is, don't put your phone in your back pocket or apply too much pressure in your front pocket (wearing tighter jeans etc). That is how I got my issue. Phone these days are extremely sensitive with its screen, so the best way is to treat the screen with extra protection.