Suggest Treatment For Shoulder Pain

Hi I'm a 23 yr old Female, 5'3" around 200lbs, I am having a sharp pulsing like pain in my left shoulder. The only thing that's changed, outside of my regular exercise, is that I started this past week teaching again a color guard team. (Flag spinning/dancing). I think I stressed a muscle in my shoulder. How should I take care of it and lessen the pain? I teach another practice tomorrow.