found root of the problem
Thank you for your time and for the response. Unfortunately, it's just a few months past its 1 year warranty. Sorry if the details are slim pickings; I'm not really that tech savvy.
After fiddling with it some more, I realized that it's a hardware problem-- the power button has become incredibly sensitive. If I graze it with my finger, it'll react as if I held it down to reset it. I thought that maybe something was lodged underneath the power button, so I unscrewed the back and spritzed some dust cleaner underneath the power button. No luck. It turns out there are apps in the google app store that enable the volume buttons to lock/unlock the screen the way a power button would in the event of a completely broken power button. The app works, except since the power button is still 'functioning' more or less, it's still difficult to work the phone for longer than 15 minutes when you can't even touch the right side of your phone without setting off the sensitive power button.
Is there any way to somehow disable the power button from working at all? That way I could just use the app to lock and unlock the screen.