Black Overlay Screen issue

So, honestly, I have no clue what this is, why it's happening, and of course how to fix it. But, I would hope to think that posting it here may get some results.

So, I've been having this issue for the past couple months, that whenever I turn on my computer, I get this black overlay screen on my main monitor (I have 2). My screen is on, and everything runs fine, it's all behind this black screen. I can't see anything behind it, I can't even see my cursor when I move it to my main monitor, it's just permanently overlaid in top of everything.

A couple temporary solutions I found, was that if I unplug and plug in my HDMI cable from my monitor, the screen comes back on for a few seconds, then goes black again, but there's a chance that it'll stay on, and usually takes 3 to 4 unplugs for it to work. The other solution is just turning off my screen, and turning it back on, but this takes many more attempts before it works.

This has been pretty irritating so far, but manageable. Only recently has this gotten even worse, that even after fixing it after boot up, it now happens randomly while on my computer. At this point, I cannot get the screen to stay on. I do suspect it *might* be Nvidia's Geforce Experience Share, considering the rare times my screen stays on after boot up, a black screen does appear, but I'm able to see my cursor, and the black screen goes away after a bit. If I click anywhere on the black screen, a message pops up saying "Nvidia's Geforce Share has stopped working". But, I'm also thinking that perhaps my monitor is dying? I've had it for a couple of years now, and it's a Dell product, which I've heard don't last much longer than a year or 2. Can anyone help, or think of what might be causing this?

Have you tried changing a cable to the monitor that goes black?

Yes, I have tried switching the HDMI cables, and it's still my main monitor that's being effected