Nexus 5 keeps having a black screen?

[nauticalsalmon]

I have a Nexus 5 and it constantly keeps having a black screen. The black screen is "on" and I can see its on. Not sure why this keeps happening. It usually happens when I'm using an app, then the app lags horribly. I go to the home screen and that lags horribly too. So I press the power button to lock the screen and try to press the power button again. Then it shows the "black screen". From then i have to hold the power button and volume up button for it to turn back on again. Then, within 20 minutes, it does it again. Can someone please help?

 

[B. Diddy]

Welcome to Android Central! Does this happen in Safe Mode? https://support.google.com/nexus/answer/2852139?hl=en. If it goes away, then some 3rd party app is causing the problem.