Rotation problems

Hi- I'm Dan in Boston, a first time contributor here. Sorry if this topic has ben discussed already, but i'm having issues with my phone rotating its screen. A few days ago it started acting erratically, and then for about a day there was an icon at the top of the screen that looked like a rectangle with little vibration lines around it. I wondered if that was some kind of indication that my rotation function was not performing correctly. Then the icon went away, but my phone's screen still rotates very erratically, taking several seconds before it will rotate after i have rotated the actual phone. Anyone hav any thoughts/suggestions?