Weird random vibrations?!

just recently my iphone started doing something really odd, it started vibrating randomly. Whether when I was using it or not, it even happens when it’s locked. Every so often I get a random buzz and it’s driving me crazy. Here’s the kicker though, I went through settings and turned all non-necessary notifications (everything but call and text) off and it still kept happening. Even worse is that when I turned all vibrations off in settings it kept happening! My phone is up to date on updates also. I have an iPhone 8 plus and there doesn’t seem to be any noticeable damage excluding a couple scratches on the screen. Any ideas on what to do or what is causing this?